Kornmeier, J., & Bach, M.. (2003). A new “Necker Cube” EEG paradigm reveals low level mechanisms in perceptual disambiguation. Journal of Vision
Plain numerical DOI: 10.1167/3.9.502
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White, K. D., Gao, J., & Zhou, Y.. (2003). Fractal statistics of perceptual switching time series. Journal of Vision
Plain numerical DOI: 10.1167/3.9.53
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“We examined perceptual switching during ambiguous depth perception, with a necker cube (10 subjects); during ambiguous motion perception, with the boneh et al rotating ball (56 subjects); and during binocular rivalry, with small moving gratings (56 subjects). autocorrelation analysis of perceptual dominance time series showed that successive response durations are essentially independent, as has long been known, on a time scale of 20 sec to 1 min (10+ responses). however, variance-sample size analysis (vss), data shuffling, and log-normal distributional properties all show that these time series behave like 1/f noise with long range correlations. vss detects lack of response independence for a range from roughly 30 to 100 responses (time scale on the order of 2 to 10 min) as evidenced in three ways. first, the hurst parameter (an index of fractal self-similarity derived from second-order statistics) was as large as 0.84. a stochastic process theoretically has this hurst parameter value = 0.5 while a predictable process, such as a sine wave, has h(2) = 1.0. secondly, shuffling the perceptual dominance periods of each time series into randomized order and then repeating the vss analysis showed that variances in the naturally ordered time series were significantly larger than corresponding variances in the shuffled time series. this was expected given their hurst correlations, and it was was shown empirically by f and binomial tests. thirdly, the histograms of h(2) for shuffled time series, randomly reordered from 1000 to 9000 times each for a subset of the data, are sharply peaked near 0.50 with a standard deviation less than 0.10. this empirically estimated sampling distribution for h(2) shows that many of the natural time series have hurst correlations unlikely to have happened by chance in random time series. power spectral densities of these time series and the good fits of theoretically expected log-normal probability density functions to data histograms further support the method of multifractal analysis.”
Meng, M., & Tong, F.. (2004). Can attention selectively bias bistable perception? Differences between binocular rivalry and ambiguous figures. Journal of Vision
Plain numerical DOI: 10.1167/4.7.2
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“It is debated whether different forms of bistable perception result from common or separate neural mechanisms. binocular rivalry involves perceptual alternations between competing monocular images, whereas ambiguous figures such as the necker cube lead to alternations between two possible pictorial interpretations. previous studies have shown that observers can voluntarily control the alternation rate of both rivalry and necker cube reversal, perhaps suggesting that bistable perception results from a common mechanism of top-down selection. however, according to the biased competition model of selective attention, attention should be able to enhance the attended percept and suppress the unattended percept. here, we investigated selective attentional modulation of dominance durations in bistable perception. observers consistently showed much weaker selective attentional control for rivalry than for necker cube reversal, even for rivalry displays that maximized the opportunities for feature-, object-, or space-based attentional selection. in contrast, nonselective control of alternation rate was comparably strong for both forms of bistable perception and corresponded poorly with estimates of selective attentional control. our results support the notion that binocular rivalry involves a more automatic, stimulus-driven form of visual competition than necker cube reversal, and as a consequence, is less easily biased by selective attention.”
Einhäuser, W., Martin, K. A. C., & König, P.. (2004). Are switches in perception of the Necker cube related to eye position?. European Journal of Neuroscience
Plain numerical DOI: 10.1111/j.1460-9568.2004.03722.x
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“The issue of the relation of eye position to perceptual reversals of the ambiguous figure of the ‘Necker cube’ dates back to necker’s original article [l.a. necker (1832) the london & edinburgh philosophical magazine and journal of science, 1, 329-337]. despite the investigations of many distinguished psychophysicists since then, the question of whether perceptual switching is a cause or a consequence of associated changes in eye position has remained a matter of debate. in the present study we overcame methodological problems that have bedevilled many previous studies. we avoided any instruction that could interfere with the human subjects’ free viewing of the necker cube, tracked the eye position precisely and used biased versions of the cube that produced unambiguous percepts to determine how each subject actually looked at the cube. we show that, under these free-viewing conditions, there is a close link between the perception of the necker cube and eye position. the average eye position of most subjects is at an extreme value at about the time when the subject’s perception switches. from the biased cube trials we can infer that the polarity of the extreme corresponds to the percept which the subject had before the switch. these data indicate a bidirectional coupling between eye position and perceptual switching so that, after a subject’s perceptual state changes, their eye position shifts to view the newly established percept. when the eye position approaches the corresponding extreme, the percept, in turn, becomes more and more likely to switch. this result suggests that the changed eye position itself might provide a negative feedback signal that suppresses the percept.”
Kornmeier, J., & Bach, M.. (2004). Early neural activity in Necker-cube reversal: Evidence for low-level processing of a gestalt phenomenon. Psychophysiology
Plain numerical DOI: 10.1046/j.1469-8986.2003.00126.x
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“Normally we experience the visual world as stable. ambiguous figures provide a fascinating exception: on prolonged inspection, the ‘necker cube’ undergoes a sudden, unavoidable reversal of its perceived front-back orientation. what happens in the brain when spontaneously switching between these equally likely interpretations? does neural processing differ between an endogenously perceived reversal of a physically unchanged ambiguous stimulus and an exogenously caused reversal of an unambiguous stimulus? a refined eeg paradigm to measure such endogenous events uncovered an early electrophysiological correlate of this spontaneous reversal, a negativity beginning at 160 ms. comparing across nine electrode locations suggests that this component originates in early visual areas. an eeg component of similar shape and scalp distribution, but 50 ms earlier, was evoked by an external reversal of unambiguous figures. perceptual disambiguation seems to be accomplished by the same structures that represent objects per se, and to occur early in the visual stream. this suggests that low-level mechanisms play a crucial role in resolving perceptual ambiguity.”
Atmanspacher, H., Filk, T., & Römer, H.. (2004). Quantum Zeno features of bistable perception. Biological Cybernetics
Plain numerical DOI: 10.1007/s00422-003-0436-4
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“A generalized quantum theoretical framework, not restricted to the validity domain of standard quantum physics, is used to model the dynamics of the bistable perception of ambiguous visual stimuli such as the necker cube. the central idea is to treat the perception process in terms of the evolution of an unstable two-state system. this gives rise to a ‘necker-zeno’ effect, in analogy to the quantum zeno effect. a quantitative relation between the involved time scales is theoretically derived. this relation is found to be satisfied by empirically obtained cognitive time scales relevant for bistable perception.”
Zhou, Y. H., Gao, J. B., White, K. D., Merk, I., & Yao, K.. (2004). Perceptual dominance time distributions in multistable visual perception. Biological Cybernetics
Plain numerical DOI: 10.1007/s00422-004-0472-8
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“Perceptual multistability, alternative perceptions of an unchanging stimulus, gives important clues to neural dynamics. the present study examined 56 perceptual dominance time series for a necker cube stimulus, for ambiguous motion, and for binocular rivalry. we made histograms of the perceptual dominance times, based on from 307 to 2478 responses per time series (median=612), and compared these histograms to gamma, lognormal and weibull fitted distributions using the kolmogorov-smirnov goodness-of-fit test. in 40 of the 56 tested cases a lognormal distribution provided an acceptable fit to the histogram (in 24 cases it was the only fit). in 16 cases a gamma distribution, and in 11 cases a weibull distribution, were acceptable but never as the only fit in either case. any of the three distributions were acceptable in three cases and none provided acceptable fits in 12 cases. considering only the 16 cases in which a lognormal distribution was rejected ( p<0.05) revealed that minor adjustments to the fourth-moment term of the lognormal characteristic function restored good fits. these findings suggest that random fractal theory might provide insight into the underlying mechanisms of multistable perceptions.”
Levy, E. K., Levy, D. E., & Goldberg, M. E.. (2004). Art and the brain: The influence of art on Roger Shepard’s studies of mental rotation. Journal of the History of the Neurosciences
Plain numerical DOI: 10.1080/09647040490885510
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“This paper explores the influence of visual sources on roger n. shepard’s 1971 mental rotation experiments and the centrality of ambiguity as one of his experimental and artistic concerns. sources include shepard’s statements about ambiguity as expressed in the book, mind sights, and a recent interview. parallel investigations of ambiguity by the contemporary artists al held and robert smithson are considered. shepard utilized a wide range of visual sources while formulating his experimental design, namely necker cube illusions, hypnopompic images, rené magritte, and m.c. escher. in addition, he drew upon key art historical theses of the time, such as ernst gombrich’s theories about schemas. for shepard as for gombrich, the world of appearances is a world of ambiguity.”
The, P. A., The, B., The, C., & Drive, O.. (2004). A Note on Approximating Distribution Functions University of Wisconsin-Madison and NBER July 2004. Observatory
Plain numerical DOI: 10.1167/8.5.12.Introduction
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“Perceptual multistability refers to the phenomenon of spontaneous perceptual switching between two or more likely interpretations of an image. although frequently explained by processes of adaptation or hysteresis, we show that perceptual switching can arise as a natural byproduct of perceptual decision making based on probabilistic (bayesian) inference, which interprets images by combining probabilistic models of image formation with knowledge of scene regularities. empirically, we investigated the effect of introducing scene regularities on necker cube bistability by flanking the necker cube with fields of unambiguous cubes that are oriented to coincide with one of the necker cube percepts. we show that background cubes increase the time spent in percepts most similar to the background. to characterize changes in the temporal dynamics of the perceptual alternations beyond percept durations, we introduce markov renewal processes (mrps). mrps provide a general mathematical framework for describing probabilistic switching behavior in finite state processes. additionally, we introduce a simple theoretical model consistent with bayesian models of vision that involves searching for good interpretations of an image by sampling a posterior distribution coupled with a decay process that favors recent to old interpretations. the model has the same quantitative characteristics as our human data and variation in model parameters can capture between-subject variation. because the model produces the same kind of stochastic process found in human perceptual behavior, we conclude that multistability may represent an unavoidable by-product of normal perceptual (bayesian) decision making with ambiguous images.”
Grossberg, S., & Swaminathan, G.. (2004). A laminar cortical model for 3D perception of slanted and curved surfaces and of 2D images: Development, attention, and bistability. Vision Research
Plain numerical DOI: 10.1016/j.visres.2003.12.009
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“A model of laminar visual cortical dynamics proposes how 3d boundary and surface representations arise from viewing slanted and curved 3d objects and 2d images. the 3d boundary representations emerge from non-classical receptive field interactions within intracortical and intercortical feedback circuits. such non-classical interactions within cortical areas v1 and v2 contextually disambiguate classical receptive field responses to ambiguous visual cues using cells that are sensitive to colinear contours, angles, and disparity gradients. remarkably, these cell types can all be explained as variants of a unified perceptual grouping circuit whose most familiar example is a 2d colinear bipole cell. model simulations show how this circuit can develop cell selectivity to colinear contours and angles, how slanted surfaces can activate 3d boundary representations that are sensitive to angles and disparity gradients, how 3d filling-in occurs across slanted surfaces, how a 2d necker cube image can be represented in 3d, and how bistable 3d necker cube percepts occur. the model also explains data about slant aftereffects and 3d neon color spreading. it shows how chemical transmitters that habituate, or depress, in an activity-dependent way can help to control development and also to trigger bistable 3d percepts and slant aftereffects. attention can influence which of these percepts is perceived by propagating selectively along object boundaries. © 2004 elsevier ltd. all rights reserved.”
Kornmeier, J., & Bach, M.. (2005). The Necker cube – An ambiguous figure disambiguated in early visual processing. Vision Research
Plain numerical DOI: 10.1016/j.visres.2004.10.006
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“How can our percept spontaneously change while the observed object stays unchanged? this happens with ambiguous figures, like the necker cube. explanations favor either bottom-up factors in early visual processing, or top-down factors near awareness. the eeg has a high temporal resolution, so event related potentials (erps) may help to throw light on these alternative explanations. however, the precise point in time of neural correlates of perceptual reversal is difficult to estimate. we developed a paradigm that overcomes this problem and found an early (120 ms) occipital erp signal correlated with endogenous perceptual reversal. parallels of ambiguous-figure-reversal to binocular-rivalry-reversals are explored. © 2004 elsevier ltd. all rights reserved.”
Van Ee, R., Van Dam, L. C. J., & Brouwer, G. J.. (2005). Voluntary control and the dynamics of perceptual bi-stability. Vision Research
Plain numerical DOI: 10.1016/j.visres.2004.07.030
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“Voluntary control and conscious perception seem to be related: when we are confronted with ambiguous images we are in some cases and to some extent able to voluntarily select a percept. however, to date voluntary control has not been used in neurophysiological studies on the correlates of conscious perception, presumably because the dynamic of perceptual reversals was not suitable. we exposed the visual system to four ambiguous stimuli that instigate bi-stable perception: slant rivalry, orthogonal grating rivalry, house-face rivalry, and necker cube rivalry. in the preceding companion paper [van ee, r. (2005). dynamics of perceptual bi-stability for stereoscopic slant rivalry and a comparison with grating, house-face, and necker cube rivalry. vision research] we focussed on the temporal dynamics of the perceptual reversals. here we examined the role of voluntary control in the dynamics of perceptual reversals. we asked subjects to attempt to hold percepts and to speed-up the perceptual reversals. the investigations across the four stimuli revealed qualitative similarities concerning the influence of voluntary control on the temporal dynamics of perceptual reversals. we also found differences. in comparison to the other rivalry stimuli, slant rivalry exhibits: (1) relatively long percept durations; (2) a relatively clear role of voluntary control in modifying the percept durations. we advocate that these aspects, alongside with its metrical (quantitative) aspects, potentially make slant rivalry an interesting tool in studying the neural underpinnings of visual awareness. © 2004 elsevier ltd. all rights reserved.”
Kanai, R., Moradi, F., Shimojo, S., & Verstraten, F. A. J.. (2005). Perceptual alternation induced by visual transients. Perception
Plain numerical DOI: 10.1068/p5245
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“When our visual system is confronted with ambiguous stimuli, the perceptual interpretation spontaneously alternates between the competing incompatible interpretations. the timing of such perceptual alternations is highly stochastic and the underlying neural mechanisms are poorly understood. we show that perceptual alternations can be triggered by a transient stimulus presented nearby. the induction was tested for four types of bistable stimuli: structure-from-motion, binocular rivalry, necker cube, and ambiguous apparent motion. while underlying mechanisms may vary among them, a transient flash induced time-locked perceptual alternations in all cases. the effect showed a dependence on the adaptation to the dominant percept prior to the presentation of a flash. these perceptual alternations show many similarities to perceptual disappearances induced by transient stimuli (kanai and kamitani, 2003 journal of cognitive neuroscience 15 664-672; moradi and shimojo, 2004 vision research 44 449-460). mechanisms linking these two transient-induced phenomena are discussed.”
Nakatani, H., & Van Leeuwen, C.. (2005). Individual differences in perceptual switching rates; The role of occipital alpha and frontal theta band activity. Biological Cybernetics
Plain numerical DOI: 10.1007/s00422-005-0011-2
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“Prolonged presentation of visually ambiguous figures leads to perceptual switching. individual switching rates show great variability. the present study compares individuals with high versus low switching rates by investigating human scalp electroencephalogram and blink rates. eight subjects viewed the necker cube continuously and responded to perceptual switching by pressing a button. frequent switchers showed characteristic occipital alpha and frontal theta band activity prior to a switch, whereas infrequent switchers did not. the alpha activity was specific to switching, the theta activity was generic to perceptual processing conditions. a negative correlation was observed between perceptual switching and blink rates. these results suggest that the ability to concentrate attentional effort on the task is responsible for the differences in perceptual switching rates.”
Slotnick, S. D., & Yantis, S.. (2005). Common neural substrates for the control and effects of visual attention and perceptual bistability. Cognitive Brain Research
Plain numerical DOI: 10.1016/j.cogbrainres.2004.12.008
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“Behavioral studies have suggested that bistable figure perception is mediated by spatial attention. we tested this hypothesis using event-related functional mri. during central fixation, two tilted squares containing coherently moving dots were presented in the left and right hemifields. in the attention condition, participants were occasionally cued to shift attention between the squares. in the perception condition, corresponding corners of the squares were connected by horizontal lines producing a perceptually bistable necker cube figure. observers reported which of the two faces appeared ‘forward’ in depth; cues elicited voluntary perceptual reversals. attending to either square during the attention condition or perceiving either square as forward during the perception condition yielded increased activity in contralateral visual areas. furthermore, voluntary shifts of attention and voluntary shifts in perceptual configuration were associated with common activity in the posterior parietal cortex, part of the frontoparietal attentional control network. these results support the hypothesis that voluntary shifts in perceptual bistability are mediated by spatial attention. © 2005 elsevier b.v. all rights reserved.”
Schrater, P.. (2005). Interpreting Bistability Using Probabilistic Inference. Gandalf.Psych.Umn.Edu
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… “… Empirically, we investigated the effect of introducing scene regularities on necker cube bistability by flanking the necker cube with fields of unambiguous cubes that are oriented to … to characterize changes in the temporal dynamics of the perceptual alternations beyond …”
Bruno, N.. (2005). Unifying sequential effects in perceptual grouping. Trends in Cognitive Sciences
Plain numerical DOI: 10.1016/j.tics.2004.11.001
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“Temporally-extended perception involves a delicate balance of constancy and change. ’This can be seen, for instance, when viewing bistable figures such as the necker cube. a recent study by gepshtein and kubovy of sequential effects in multistable dot lattices demonstrates constancy and change within the same set of data. they propose that these opposing trends might be explained by the same single factor: a persistent random orientation bias that is intrinsic to brain activity. this proposal could form the basis for a new account of multistability.”
Van Ee, R.. (2005). Dynamics of perceptual bi-stability for stereoscopic slant rivalry and a comparison with grating, house-face, and Necker cube rivalry. Vision Research
Plain numerical DOI: 10.1016/j.visres.2004.07.039
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“A way to study conscious perception is to expose the visual system to an ambiguous stimulus that instigates bi-stable perception. this provides the opportunity to study neural underpinnings related to the percepts rather than to the stimulus. we have recently developed a slant-rivalry paradigm that has beneficial metrical (quantitative) aspects and that exhibits temporal aspects of perceptual reversals that seemed to be under considerable voluntary control of the observer. here we examined a range of different aspects of the temporal dynamics of the perceptual reversals of slant rivalry and we compared these with the dynamics of orthogonal grating rivalry, house-face rivalry, and necker cube rivalry. we found that slant rivalry exhibits a qualitatively similar pattern of dynamics. the drift of the perceptual reversal rate, both across successive experimental repetitions, and across successive 35-s portions of data were similar. the sequential dependence of the durations of perceptual phases, too, revealed very similar patterns. the main quantitative difference, which could make slant rivalry a useful stimulus for future neurophysiological studies, is that the percept durations are relatively long compared to the other rivalry stimuli. in the paper that accompanies this paper [van ee, r., van dam, l. c. j., brouwer, g. j. (2005). voluntary control and the dynamics of perceptual bi-stability. vision research, doi:10.1016/j.visres.2004.07.030] we focused on the role of voluntary control in the dynamics of perceptual reversals. © 2004 elsevier ltd. all rights reserved.”
Maloney, L. T., Martello, M. F. D., Sahm, C., & Spillmann, L.. (2005). Past trials influence perception of ambiguous motion quartets through pattern completion. Proceedings of the National Academy of Sciences
Plain numerical DOI: 10.1073/pnas.0407157102
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“There are many celebrated examples of ambiguous perceptual configurations such as the necker cube that abruptly and repeatedly ‘switch’ among possible perceptual states. when such ambiguous configurations are presented intermittently, observers tend to see the same perceptual state on successive trials. the outcome of each trial apparently serves to ‘prime’ the outcome of the following. we sought to determine how long the influence of a past trial persists by using ambiguous motion quartets as stimuli. we found large, significant effects of all four most recent trials, but the results were not consistent with any priming model. the results could be explained instead as perceptual completion of two kinds of temporal patterns, repeating and alternating. we conclude that the visual system does not passively remember perceptual state: it analyzes recent perceptual history and attempts to predict what will come next. these predictions can alter what is seen.”
Işoǧlu-Alkaç, Ü., & Strüber, D.. (2006). Necker cube reversals during long-term EEG recordings: Sub-bands of alpha activity. International Journal of Psychophysiology
Plain numerical DOI: 10.1016/j.ijpsycho.2005.05.002
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“Reversible figures, such as the necker cube, make up a well-known class of visual phenomena in which an invariant stimulus pattern gives rise to at least two different perceptual interpretations. a better understanding of the neurophysiological processes underlying perceptual reversals might help to disentangle bottom-up from top-down influences on multistable perception. recently, we reported alpha activity decrease during multistable visual perception. the aim of the present study was to define more specifically the functional roles of the eeg alpha band during the perception of necker cube reversals by subdividing the extended alpha band into three sub-bands (lower-1 alpha, lower-2 alpha, upper alpha). we employed a long-term recording condition, during which 10 healthy participants observed the necker cube for approximately 60 min and responded by pressing a button to any perceived reversal. the results showed a reversal induced alpha desynchronization for the lower alpha bands, with the lower-2 alpha desynchronization differing across the time course of the experiment. the upper alpha band demonstrated no reliable effects. it is concluded that the lower-1 alpha desynchronization reflects an automatic arousal reaction which triggers attentional processing in a bottom-up manner, whereas the lower-2 alpha desynchronization is related to attentional processes that are achieved by top-down control with limited resources. the lack of reliable effects in the upper alpha band is presumably due to the relatively low semantic task demands in figure reversal. © 2005 elsevier b.v. all rights reserved.”
Mathes, B., Strüber, D., Stadler, M. A., & Basar-Eroglu, C.. (2006). Voluntary control of Necker cube reversals modulates the EEG delta- and gamma-band response. Neuroscience Letters
Plain numerical DOI: 10.1016/j.neulet.2006.03.063
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“Reversible figures such as the necker cube make up a well-known class of visual phenomena in which an invariant stimulus pattern gives rise to at least two different perceptual interpretations. former eeg studies of our research group demonstrated a reversal-related delta response and a frontal enhancement of gamma activity during multistable perception which has been interpreted as signaling attentional top-down processes. the aim of the present study was to investigate the functional involvement of delta and gamma activity in top-down processes more explicitly by asking 21 healthy participants to bring the reversal rate under voluntary control during viewing of the necker cube. slowing down the reversal rate should be accomplished by focussing attention to the currently perceived alternative while speeding up should be accomplished by shifting attention as rapidly as possible from one perspective to the other. eeg was recorded from frontal, central, parietal, and occipital locations of both hemispheres. the data was analysed on the single-sweep level in the delta and gamma frequency range. the results showed that both delta response and gamma power were larger during slowing down than speeding up the reversal rate. these findings may indicate that more attentional resources have to be allocated by the cognitive system in order to prevent a reversal by means of focussed attention than to initiate a reversal by attentional shifts. © 2006 elsevier ireland ltd. all rights reserved.”
Haijiang, Q., Saunders, J. A., Stone, R. W., & Backus, B. T.. (2006). Demonstration of cue recruitment: Change in visual appearance by means of Pavlovian conditioning. Proceedings of the National Academy of Sciences
Plain numerical DOI: 10.1073/pnas.0506728103
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“Until half a century ago, associative learning played a fundamental role in theories of perceptual appearance [berkeley, g. (1709) an essay towards a new theory of vision (dublin), 1st ed.]. but starting in 1955 [gibson, j. j. & gibson, e. j. (1955) psychol. rev. 62, 32-41], most studies of perceptual learning have not been concerned with association or appearance but rather with improvements in discrimination ability. here we describe a ‘cue recruitment’ experiment, which is a straightforward adaptation of pavlov’s classical conditioning experiment, that we used to measure changes in visual appearance caused by exposure to novel pairings of signals in visual stimuli. trainees viewed movies of a rotating wire-frame (necker) cube. this stimulus is perceptually bistable. on training trials, depth cues (stereo and occlusion) were added to force the perceived direction of rotation. critically, an additional signal was also added, contingent on rotation direction. stimuli on test trials contained the new signal but not the depth cues. over 45 min, two of the three new signals that we tested acquired the ability to bias perceived rotation direction on their own. results were consistent across the eight trainees in each experiment, and the new cue’s effectiveness was long lasting. whereas most adaptation aftereffects on appearance are opposite in direction to the training stimuli, these effects were positive. an individual new signal can be recruited by the visual system as a cue for the construction of visual appearance. cue recruitment experiments may prove useful for reexamining of the role of experience in perception.”
Kornmeier, J., & Bach, M.. (2006). Bistable perception – along the processing chain from ambiguous visual input to a stable percept. International Journal of Psychophysiology
Plain numerical DOI: 10.1016/j.ijpsycho.2006.04.007
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“The observation of an ambiguous figure leads to spontaneous perceptual reversals while the observed picture stays unchanged. some erp studies on ambiguous figures report a p300-like component correlated with perceptual reversals supporting a top-down explanation, while other studies found early visual erp components supporting a bottom-up explanation. based on an experimental paradigm that permits a high temporal resolution of the endogenous reversal event, we compared endogenous necker-cube reversals with exogenously-induced reversals of unambiguous cube variants. for both reversal types, we found a chain of erp components with the following characteristics: (1) an early occipital erp component (130 ms) is restricted to endogenous reversals. (2) all subsequent components also appear with exogenously-induced reversals, however 40-90 ms earlier than their endogenous counterparts. (3) the latency difference between reversal types is also reflected in the timing of manual reactions, which occur 100-130 ms after p300-like components. the results suggest that the p300-like component is the same as found in other erp studies on ambiguous figures. this component does not reflect the reversal per se, but rather its cognitive analysis, 300 ms after a change of the representation in early visual areas. the presented erp chains integrate the different erp results and allow to pinpoint the steps where top-down mechanisms begin to exert their influence. © 2006 elsevier b.v. all rights reserved.”
Van Dam, L. C. J., & Van Ee, R.. (2006). The role of saccades in exerting voluntary control in perceptual and binocular rivalry. Vision Research
Plain numerical DOI: 10.1016/j.visres.2005.10.011
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“We have investigated the role of saccades and fixation positions in two perceptual rivalry paradigms (slant rivalry and necker cube) and in two binocular rivalry paradigms (grating and house-face rivalry), and we compared results obtained from two different voluntary control conditions (natural viewing and hold percept). we found that for binocular rivalry, rather than for perceptual rivalry, there is a marked positive temporal correlation between saccades and perceptual flips at about the moment of the flip. across different voluntary control conditions the pattern of temporal correlation did not change (although the amount of correlation did frequently, but not always, change), indicating that subjects do not use different temporal eye movement schemes to exert voluntary control. analysis of the fixation positions at about the moment of the flips indicates that the fixation position by itself does not determine the percept but that subjects prefer to fixate at different positions when asked to hold either of the different percepts. © 2005 elsevier ltd. all rights reserved.”
van Ee, R., Noest, A. J., Brascamp, J. W., & van den Berg, A. V.. (2006). Attentional control over either of the two competing percepts of ambiguous stimuli revealed by a two-parameter analysis: Means do not make the difference. Vision Research
Plain numerical DOI: 10.1016/j.visres.2006.03.017
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“We studied distributions of perceptual rivalry reversals, as defined by the two fitted parameters of the gamma distribution. we did so for a variety of bi-stable stimuli and voluntary control exertion tasks. subjects’ distributions differed from one another for a particular stimulus and control task in a systematic way that reflects a constraint on the describing parameters. we found a variety of two-parameter effects, the most important one being that distributions of subjects differ from one another in the same systematic way across different stimuli and control tasks (i.e., a fast switcher remains fast across all conditions in a parameter-specified way). the cardinal component of subject-dependent variation was not the conventionally used mean reversal rate, but a component that was oriented-for all stimuli and tasks-roughly perpendicular to the mean rate. for the necker cube, we performed additional experiments employing specific variations in control exertion, suggesting that subjects have to a considerable extent independent control over the reversal rate of either of the two competing percepts. © 2006 elsevier ltd. all rights reserved.”
Gao, J. B., Billock, V. A., Merk, I., Tung, W. W., White, K. D., Harris, J. G., & Roychowdhury, V. P.. (2006). Inertia and memory in ambiguous visual perception. Cognitive Processing
Plain numerical DOI: 10.1007/s10339-006-0030-5
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“Perceptual multistability during ambiguous visual perception is an important clue to neural dynamics. we examined perceptual switching during ambiguous depth perception using a necker cube stimulus, and also during binocular rivalry. analysis of perceptual switching time series using variance-sample size analysis, spectral analysis and time series shuffling shows that switching times behave as a 1/f noise and possess very long range correlations. the long memory feature contrasts sharply with the traditional satiation models of multistability, where the memory is not incorporated, as well as with recently published models of multistability and neural processing, where memory is excluded. on the other hand, the long memory feature favors the concept of ‘dynamic core’ or coalition of neurons, where neurons form transient coalitions. perceptual switching then corresponds to replacement of one coalition of neurons by another. the inertia and memory measures the stability of a coalition: a strong and stable coalition has to be won over by another similarly strong and stable coalition, resulting in long switching times. the complicated transient dynamics of competing coalitions of neurons may be addressable using a combination of functional imaging, measurement of frequency-tagged magnetoencephalography and frequency-tagged encephalography, simultaneous recordings of groups of neurons in many areas of the brain, and concepts from statistical mechanics and nonlinear dynamics theory.”
Majumdar, N. S., Pribram, K. H., & Barrett, T. W.. (2006). Time frequency characterization of evoked brain activity in multiple electrode recordings. IEEE Transactions on Biomedical Engineering
Plain numerical DOI: 10.1109/TBME.2006.883733
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“This paper explores global time frequency approaches to eeg data analysis with the wigner distribution function and the symmetric ambiguity function. the task chosen was to characterize the activity profile of eeg signals in sample frontal, central and occipital electrodes from human subjects, coincident with the perception of a reversal in the orientation of a bistable necker cube figure. the result of this analysis has implications for blind signal processing as the goal was to identify an unknown input source eliciting the observed eeg signals. the methods demonstrate an internally initiated eeg signal source not tied to a regularly anticipated external source. the results demonstrate the general applicability of the methods for a wide variety of neural and biological signals and systems. the findings can be summarized as the observation of high energy activity patterns in terms of significant dissimilarities in the wave-form, both in time and frequency, in the frontal and occipital electrodes, approximately 200–609 ms prior to the appearance of the premotor potentials in the medial electrodes. [abstract from author] copyright of ieee transactions on biomedical engineering is the property of ieee and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder’s express written permission. however, users may print, download, or email articles for individual use. this abstract may be abridged. no warranty is given about the accuracy of the copy. users should refer to the original published version of the material for the full abstract. (copyright applies to all abstracts)”
Kennard, C.. (2006). Vision, Illusions, and Reality. International Review of Neurobiology
Plain numerical DOI: 10.1016/S0074-7742(06)74004-1
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“Since vision is our primary sense, it is not surprising that a large part of the human brain is devoted to processing the image of our visual world to generate visual percept. however, it is wrong to consider that our visual brain always provides us with a percept that is true to the external visual world. rather, it actively participates in constructing what we see. our visual percept, obtained from the information it receives from the two eyes, may sometimes be distorted as a result of physiological interactions among neurons in the visual brain due to the pattern of their connections. this is best exemplified by the study of visual illusions, for example, in the zöllner illusion parallel lines appear bowed or nonparallel when a series of short orthogonal lines are added due to lateral interactions between orientation columns (fig. 1). alternatively at other times, distortions arise from the generation of hypotheses by the visual brain about the visual world, for example, when the two-dimensional metastable illusion (necker cube) is viewed it appears three-dimensional, but its forward face repeatedly changes between two alternatives (fig. 2). as in the rest of science, these hypotheses may not always be correct and individuals may require other sensory inputs (e.g., tactile) to determine reality. the visual brain also has to restrict what we see since processing all the visual information received by our eyes would require a visual brain many times larger than available to us. we, therefore, focus attention and hence visual processing on a restricted region of the visual world. © 2006 elsevier inc. all rights reserved.”
Shimada, Y., Meguro, K., Kasai, M., Shimada, M., Ishii, H., Yamaguchi, S., & Yamadori, A.. (2006). Necker cube copying ability in normal elderly and Alzheimer’s disease. A community-based study: The Tajiri project. Psychogeriatrics
Plain numerical DOI: 10.1111/j.1479-8301.2006.00121.x
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“Background: the purpose of this study was to investigate the ability of normal elderly participants and patients with alzheimer’s disease to copy the necker cube. method: one hundred and seventy elderly participants were randomly selected from the town of tajiri, northern japan, and were classified into three groups based on the clinical dementia rating (cdr): cdr 0, healthy; cdr 0.5, questionable dementia; and cdr 1 and 2, mild and moderate dementia. dementia patients (cdr 1 and 2) met the criteria of probable ad of the nincds-adrda. using eight original criteria, we examined their ability to copy the necker cube. results: most cdr 0 participants could at least succeed in copying a simple cube. about a half of the ad patients could not draw a three-dimensional figure. among the cdr 0.5 participants, we found a ‘two-peak’ distribution. conclusion: copying the necker cube may be one useful task for the detection of very mild alzheimer’s disease. © 2006 japanese psychogeriatric society.”
Nakatani, H., & Van Leeuwen, C.. (2006). Transient synchrony of distant brain areas and perceptual switching in ambiguous figures. Biological Cybernetics
Plain numerical DOI: 10.1007/s00422-006-0057-9
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“We studied the relationship between perceptual switching in the necker cube and long-distance transient phase synchronization in eeg. transient periods of response related synchrony between parietal and frontal areas were observed. they start 800-600, ms prior to the switch response and occur in pairs. four types of pairs could be distinguished, two of which are accompanied by transient alpha band activity in the occipital area. the results indicate that perceptual switching processes involve parietal and frontal areas; these are the ones that are normally associated with various cognitive processes. sensory information in the visual areas is involved in some, but not in all, of switching processes. the intrinsic variability, as well as the participating areas, points to the role of strategic cognitive processes in perceptual switching.”
Bruno, N., Jacomuzzi, A., Bertamini, M., & Meyer, G.. (2007). A visual-haptic Necker cube reveals temporal constraints on intersensory merging during perceptual exploration. Neuropsychologia
Plain numerical DOI: 10.1016/j.neuropsychologia.2006.01.032
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“When viewing a three-dimensional necker cube with one eye, participants can experience illusory reversals even while they feel the cube with their hands. this surprising property of the visual-haptic necker cube affords a unique opportunity to investigate temporal constraints on interactions between vision and touch during extended observation of a three-dimensional object. our observers reported reversals while they viewed the cube and, at the same time, they either held it with two-finger grips, felt it with while their hands remained stationary, or actively explored it by moving one hand. consistent with a multisensory approach to three-dimensional form perception, touch had a clear effect on both the number and the duration of illusory percepts. additionally, when observers alternated between stationary and moving periods during exploration, transitions from stationary to moving-hand haptics played a crucial role in inhibiting illusory reversals. a temporal analysis of the probability of first reversals occurring after different types of motor transition revealed a ‘vetoing window’ initiating approximately 2 s after the transition and lasting at least another 1-2 s. implications for multisensory processes during exploration are discussed. © 2006.”
Schoth, F., Waberski, T. D., Krings, T., Gobbele, R., & Buchner, H.. (2007). Cerebral processing of spontaneous reversals of the rotating Necker cube. NeuroReport
Plain numerical DOI: 10.1097/WNR.0b013e3281668007
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“The cerebral processing of spontaneous perceptive reversals of the rotating necker cube was studied in humans by combined functional mri and electroencephalography. these reversals prefer certain positions of the necker cube and can be studied without external reference of the perception. functional mri revealed six bilaterally active regions in the visual, parietal, and premotor cortex. a new method determined phase-locked electroencephalography-activations in the regions of interest and showed a significant stimulus-locked activity that started in the left brodmann area 18. this activity started 38 ms after passing the symmetric position of the necker cube and spread along the dorsal stream. we suggest that a further portion of the event-related potential signal reflects additional top-down processing, dependent on the position of the necker cube.”
Pitts, M. A., Nerger, J. L., & Davis, T. J. R.. (2007). Electrophysiological correlates of perceptual reversals for three different types of multistable images. Journal of Vision
Plain numerical DOI: 10.1167/7.1.6
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“Electrophysiological recordings were made in 21 observers to investigate whether differences in signature components (p1, n1, selection negativity [sn]) would be revealed during perceptual reversals of three different multistable figures. using a lattice of necker cubes as a stimulus, j. kornmeier and m. bach (2004, 2005) reported differences in p1 amplitudes as well a broad reversal-related negativity occurring 200-400 ms poststimulus. the current study investigated whether these event-related potentials of necker cube reversals represent general ‘perceptual switching’ mechanisms and would, therefore, be common to other types of multistable figures. three different types of multistable stimuli were utilized: a modified rubin’s face/vase, a modified schröder’s staircase, and a novel natural stimulus, lemmo’s cheetahs. results revealed the broad reversal-related negativity for the face/vase and the reversible staircase but not for the cheetahs. this component is comparable to the sn in polarity, latency, and scalp topography. an effect of early visual spatial attention on figure reversals was suggested by an analysis of the occipital p1 and n1 components. the p1, n1, or both were enhanced for trials in which the observer reported perceptual reversals compared with trials in which no reversals were reported for the face/vase and reversible staircase stimuli. these results support a model of multistable perception in which changes in early spatial attention (indicated by p1 and n1 enhancement) modulate perceptual reversals (indicated by the reversal negativity or sn).”
Backus, B. T., & Haijiang, Q.. (2007). Competition between newly recruited and pre-existing visual cues during the construction of visual appearance. Vision Research
Plain numerical DOI: 10.1016/j.visres.2006.12.008
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“During perception, conflicting visual cues often trade against each other. recent cue recruitment experiments show that the visual system can be conditioned to use artificial visual cues during the perception of a bistable stimulus. does the visual system treat the new cue as an independent source of information, separate from the long-trusted cues that were used to train it? if so, presence of the long-trusted cue should not be sufficient to block the new cue’s effect. here, we show that a newly recruited cue (stimulus location) and a long-trusted, pre-existing cue (binocular disparity) trade against each other: they contribute simultaneously to the direction of perceived 3d rotation of a necker cube. we also show that the new position cue was based primarily on retinal position, so early visual areas may mediate the cue’s effect. © 2006 elsevier ltd. all rights reserved.”
Long, G. M., & Moran, C. J.. (2007). How to keep a reversible figure from reversing: Teasing out top-down and bottom-up processes. Perception
Plain numerical DOI: 10.1068/p5630
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“The nature of processes underlying our perception of reversible figures was examined through two experiments investigating the effects of prior exposure conditions on an observer’s report of figural reversal. in experiment 1, observers were adapted over several minutes to an unambiguous version of a rotating necker cube prior to the presentation of the standard ambiguous figure. results indicated that adaptation produced an immediate bias to perceive the ambiguous figure in the opposite configuration (ie reverse bias) and to reduce reports of reversal over the test period. the introduction of a brief delay between the adaptation and test periods revealed that this bias is a highly transient effect and is only clearly evident when the adaptation and test figures are matched in size. in experiment 2, observers were primed with an unambiguous figure for a few seconds prior to the presentation of the standard ambiguous figure. in this case, the obtained bias strongly favored the observer’s reporting the ambiguous figure to be in the same configuration as the adapting figure (ie positive bias); and neither introducing a delay period nor changing figure size had any effect. we conclude that these experiments reveal the distinct roles of transient, retinally localized neural processes as well as more stable, global processes under specifiable conditions.”
Mooney, G., & McIntyre, D.. (2007). Why this book. In The Economics of Health Equity
Plain numerical DOI: 10.1017/CBO9780511544460.002
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“Behavioral studies have suggested that bistable figure perception is mediated by spatial attention. we tested this hypothesis using event-related functional mri. during central fixation, two tilted squares containing coherently moving dots were presented in the left and right hemifields. in the attention condition, participants were occasionally cued to shift attention between the squares. in the perception condition, corresponding corners of the squares were connected by horizontal lines producing a perceptually bistable necker cube figure. observers reported which of the two faces appeared ‘forward’ in depth; cues elicited voluntary perceptual reversals. attending to either square during the attention condition or perceiving either square as forward during the perception condition yielded increased activity in contralateral visual areas. furthermore, voluntary shifts of attention and voluntary shifts in perceptual configuration were associated with common activity in the posterior parietal cortex, part of the frontoparietal attentional control network. these results support the hypothesis that voluntary shifts in perceptual bistability are mediated by spatial attention.”
Radilova, J., Taddei-Ferretti, C., Musio, C., Santillo, S., Cibelli, E., Cotugno, A., & Radil, T.. (2007). Reversal of “cubic” and “cylindric” Figures. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Plain numerical DOI: 10.1007/978-3-540-75555-5_14
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“Spontaneous figure reversal of ambiguous patterns was analyzed in humans by presenting ‘necker-cube’-like, or ‘drum’-like figures having square or round shaped ‘front’ and ‘rear’ surfaces, and either large or small ‘depth’. the figures were perceived alternately according to one or the other of two possible mental orientation-interpretations. the subjects signalled the instant of subjective pattern-reversals. results: perceptual intervals corresponding to both interpretations of ‘drum’ were longer than those of ‘cube’; the perceived ‘depth’ of the figures was less relevant for reversal timing (‘deeper’ figures reversed only slightly more slowly and the corresponding intervals were somewhat longer). although the shape of ‘front’ and ‘rear’ surfaces was not a crucial geometrical feature for representing the three-dimensional nature of the patterns on the two-dimensional stimulus plane, it markedly influenced the timing of figure reversals. more, or longer information processing steps should needed for perceptual-cognitive representations of curvilinear patterns in comparison with rectangular ones. © 2007 springer-verlag berlin heidelberg.”
Goebel, P. M., & Vincze, M.. (2007). Vision for cognitive systems: A new compound concept connecting natural scenes with cognitive models. In IEEE International Conference on Industrial Informatics (INDIN)
Plain numerical DOI: 10.1109/INDIN.2007.4384859
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“Vision, as a key perceptional capability for cognitive systems relates to rather difficult problems -such as visual object recognition, representation, categorization, and scene understanding. state-of-the-art solutions, using object appearance based models, already reached certain maturity. they achieve excellent recognition performance and provide learning structures that are subsequently utilized for object recognition and tracking. however, in context of object topology understanding for cognitive tasks, these methods cannot be directly compared with human performance, because it is obvious that appearance based methods do not contribute to understanding of structures in 3d. research findings from infant psychology and animal investigation give evidence for using hierarchical models of object representation, based on image primitives e.g. such as edges, corners, shading or homogeneity of object colors. it is the objective of this paper to present an approach based on both, findings from biological studies and cognitive science, as enablers for autonomous cognitive investigation of natural scenes and their understanding. we present the architecture of a compound cognitive framework and its first behavioral level with the implementation of a vision model of the mammalian striate visual cortex in five layers. the proposed implementation is exemplified with an object similar to the necker cube.”
Ramachandran, V. S., & Rogers-Ramachandran, D.. (2007). Ambiguities and Perception. Scientific American Mind
Plain numerical DOI: 10.1038/scientificamericanmind1007-18
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“The article focuses on the association between perception and intellectual problem solving. it is stated that many visual illusions exploit ambiguity to titillate the senses. according to german physicist hermann von helmholtz, perception has a good deal in common with intellectual problem solving. some illusionary images are cited as examples of how top-down influences from higher brain centers-where such perceptual tokens as ‘old’ and ‘young’ are encoded-can ful text : what uncertainty tells us about the brain the brain abhors ambiguity, yet we are curiously attracted to it. many famous visual illusions exploit ambiguity to titillate the senses. resolving uncertainties creates a pleasant jolt in your brain, similar to the one you experience in the ‘eureka!’ moment of solving a problem. such observations led german physicist, psychologist and ophthalmologist hermann von helmholtz to point out that perception has a good deal in common with intellectual problem solving. more recently, the idea has been revived and championed eloquently by neuropsychologist richard l. gregory of the university of bristol in england. so-called bistable figures, such as the mother-in-law/wife (a) and faces/vase (b) illusions, are often touted in textbooks as the prime example of how top-down influences (preexisting knowledge or expectations) from higher brain centers such perceptual tokens as ‘old’ and ‘young’ are encoded influence perception. laypeople often take this to mean you can see anything you want to see, but this is nonsense ironically, this view contains more truth than most of our colleagues would allow. fun flips consider the simple case of the necker cube (c and variation in d). you can view this illusion in one of two ways pointing up or pointing down. with a little practice, you can flip between these alternate percepts at will (still, it is great fun when it flips spontaneously; it feels like an amusing practical joke has been played on you). in fact, the drawing is compatible not only with two interpretations, as is commonly believed; there is actually an infinite set of trapezoidal shapes that can produce exactly the same retinal image, yet the brain homes in on a cube without hesitation. note that at any time, you see only one or the other. the visual system appears to struggle to determine which of two cubes the drawing represents, but it has already solved the much larger perceptual problem by rejecting trillions of other configurations that could give…”
Braun, J., & Pastukhov, A.. (2007). Further differences between positive and negative priming in the perception of ambiguous patterns. In The Annual Meeting of the Vision Sciences Society
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“In repeated viewing of ambiguous patterns, perception is biased by positive and negative priming effects. in a companion abstract, we report that positive priming lasts 20-30 times longer than negative priming. here, we exploit this difference to disentangle positive and negative priming by a given pattern. to establish generality, we compare five kinds of patterns (kinetic-depth-effect or kde, two instances of binocular rivalry, necker cube, anstis dots). nine observers participated. for all kinds of ambiguous patterns, an unambiguous version negatively primes the ambiguous pattern: the two are rarely perceived in the same way (psurvival ≈ 0), if no pause intervenes. when a pause is introduced, negative priming is no longer evident (psurvival ≈ 0.5). when a pause separates two ambiguous patterns, positive priming is found in all cases (psurvival ≈ 1.0). thus, only ambiguous patterns appear to leave a ‘perceptual memory’ which may bias subsequent perceptions. to further study this particularity of ambiguous patterns, we generated kde patterns with varying degrees of ‘bias’ for one percept or another (quantified separately for each observer). the dominance fraction under continuous viewing served as a measure (50% for unbiased and 100% for completely biased). next, we asked how a biased pattern (‘prime’) affects perception of a subsequent ambiguous pattern (‘probe’)? with no pause between probe and prime, negative priming (psurvival ≈ 0) gradually gives way to positive priming (psurvival ≈ 1.0) as prime bias decreases. when a pause between probe and prime allows negative priming decay, statistically identical positive priming (psurvival > 0.5) obtains for prime bias 50% to 97%. no priming (psurvival ≈ 0.5) occurs for 100% bias (unambiguous kde). we conclude that ambiguous patterns engage additional levels of processing where they leave a ‘perceptual memory’. unambiguous patterns do not engage these levels and leave no ‘memory’.”
Sundareswara, R., & Schrater, P. R.. (2008). Perceptual multistability predicted by search model for Bayesian decisions. Journal of Vision
Plain numerical DOI: 10.1167/8.5.12
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“Perceptual multistability refers to the phenomenon of spontaneous perceptual switching between two or more likely interpretations of an image. although frequently explained by processes of adaptation or hysteresis, we show that perceptual switching can arise as a natural byproduct of perceptual decision making based on probabilistic (bayesian) inference, which interprets images by combining probabilistic models of image formation with knowledge of scene regularities. empirically, we investigated the effect of introducing scene regularities on necker cube bistability by flanking the necker cube with fields of unambiguous cubes that are oriented to coincide with one of the necker cube percepts. we show that background cubes increase the time spent in percepts most similar to the background. to characterize changes in the temporal dynamics of the perceptual alternations beyond percept durations, we introduce markov renewal processes (mrps). mrps provide a general mathematical framework for describing probabilistic switching behavior in finite state processes. additionally, we introduce a simple theoretical model consistent with bayesian models of vision that involves searching for good interpretations of an image by sampling a posterior distribution coupled with a decay process that favors recent to old interpretations. the model has the same quantitative characteristics as our human data and variation in model parameters can capture between-subject variation. because the model produces the same kind of stochastic process found in human perceptual behavior, we conclude that multistability may represent an unavoidable by-product of normal perceptual (bayesian) decision making with ambiguous images.”
Elman, I., Chi, W. H., Gurvits, T. V., Ryan, E. T., Lasko, N. B., Lukas, S. E., & Pitman, R. K.. (2008). Impaired Reproduction of Three-Dimensional Objects by Cocaine-Dependent Subjects. The Journal of Neuropsychiatry and Clinical Neurosciences
Plain numerical DOI: 10.1176/jnp.2008.20.4.478
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“This study employed a perceptual-motor task of figure copying in 27 cocaine-dependent, 26 marijuana-abusing or dependent, and 33 healthy subjects. cocaine-dependent and healthy individuals did not differ in their scores on the copying of a two-dimensional diamond and a cross. in contrast, cocaine-dependent subjects displayed significantly poorer ability to copy a three-dimensional necker cube, a smoking pipe, a hidden line elimination cube, a pyramid, and a dissected pyramid. marijuana users’ performance on all copied figures was comparable to that of the healthy comparison subjects. considering that decreased three-dimensional copying ability has been found to be associated with fatal injuries, further studies are needed to investigate possible underlying mechanisms (e.g., parietal lobe damage) and their role in the pathophysiology of cocaine dependence.”
Sinkiewicz, W., Błaejewski, J., Bujak, R., Kubica, J., & Dudziak, J.. (2008). Immunoglobulin E in patients with ischemic heart disease. Cardiology Journal
Plain numerical DOI: 10.1016/j.visres.2003.12.009
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“A model of laminar visual cortical dynamics proposes how 3d boundary and surface representations arise from viewing slanted and curved 3d objects and 2d images’. the 3d boundary representations emerge from non-classical receptive field interactions within intracortical and intercortical feedback circuits. such non-classical interactions within cortical areas v1 and v2 contextually disambiguate classical receptive field responses to ambiguous visual cues using cells that are sensitive to colinear contours, angles, and disparity gradients. remarkably, these cell types can all be explained as variants of a unified perceptual grouping circuit whose most familiar example is, 2d colinear bipole cell. model simulations show how this circuit can develop cell selectivity to colinear contours and angles, how slanted surfaces can activate 3d boundary representations that are sensitive to angles and disparity gradients, how 3d filling-in occurs across slanted surfaces, how a 2d necker cube image can be represented in 3d, and how bistable 3d necker cube percepts occur. the model also explains data about slant aftereffects and 3d neon color spreading. it shows how chemical transmitters that habituate, or depress, in an activity-dependent way can help to control development and also to trigger bistable 3d percepts and slant aftereffects. attention can influence which of these percepts is perceived by propagating selectively along object boundaries. (c) 2004 elsevier ltd. all rights reserved.”
Hardin, J. C., & Creusere, C. D.. (2008). Objective analysis of temporally varying audio quality metrics. In Conference Record – Asilomar Conference on Signals, Systems and Computers
Plain numerical DOI: 10.1109/ACSSC.2008.5074616
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“Perception of ambiguous figures is unstable and alternates repeatedly between possible interpretations. some approaches to explaining this phenomenon have, so far, assumed low-level bottom- up mechanisms like adaptation and mutual inhibition of underlying neural assemblies. in contrast, less precise top-down approaches assume high-level attentional control mechanisms generalised across sensory modalities. in the current work we focused on specific aspects of the top-down approach. in a first study we used dwell times (periods of transiently stable percepts) and the parameters of dwell time distribution functions to compare the dynamics of perceptual alternations between visual (necker cube) and auditory ambiguity (verbal transformation effect). in a second study we compared the endogenous alternation dynamics of the necker cube with parameters from two attention tasks with different regimes of temporal dynamics. the first attention task (d2) is characterised by endogenous self-paced dynamics, similar to the dynamics underlying perceptual alternations of ambiguous figures, and we found clear correlations between dwell time parameters (necker cube) and processing speed (d2 task). the temporal dynamics of the second (go/no-go) attention task, in contrast, are exogenously governed by the stimulus protocol, and we found no statistically significant correlation with the necker cube data. our results indicate that both perceptual instability and higher-level attentional tasks are linked to endogenous brain dynamics on a global coordinating level beyond sensory modalities.”
Rinzel, J.. (2008). Alternating perceptions of ambiguous scenes: what’s out there?. BMC Neuroscience
Plain numerical DOI: 10.1186/1471-2202-9-S1-L1
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“When visualizing an ambiguous scene (such as the necker cube) one may perceive ongoing random alternations between the possible interpretations. dynamical models implement competition as reciprocal inhibition between neuronal populations; dominance alternates while slow negative feedback, adaptation, sets the basic time scale (seconds) for switching. when adaptation is strong enough it overcomes dominance and alternations occur intrinsically and periodically; noise perturbs the regularity. in a different framework, with attractor-based dynamics, adaptation is weak and switches are induced by noise operating on a bistable system. we find that statistics of the observed alternations provide constraints that favor an operating range near the transition zone between the parameter regimes for the two mechanisms. in some paradigms one can manipulate stimulus cues to bias the competition away from equal dominance. we have proposed that the percentage of time dominant is a measure for the likelihood of valid interpretation of the scene.”
Shapley, R., & Maertens, M.. (2008). Angle alignment evokes perceived depth and illusory surfaces. Perception
Plain numerical DOI: 10.1068/p5987
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“There is a distinct visual process that triggers the perception of illusory surfaces and contours along the intersections of aligned, zigzag line patterns. such illusory contours and surfaces are qualitatively different from illusory contours of the kanizsa type. the illusory contours and surfaces in this case are not the product of occlusion and do not imply occlusion of one surface by another. rather, the aligned angles in the patterns are combined by the visual system into the perception of a fold or a 3-d corner, as of stairs on a staircase or a wall ending on a floor. the depth impression is ambiguous and reversible like the necker cube. such patterns were used by american indian artists of the akimel o’odham (pima) tribe in basketry, and also by modern european and american artists like josef albers, bridget riley, victor vasarely, and frank stella. our research aims to find out what manipulations of the visual image affect perceived depth in such patterns in order to learn about the perceptual mechanisms. using paired comparisons, we find that human observers perceive depth in such patterns if, and only if, lines in adjacent regions of the patterns join to form angles, and also if, and only if, the angles are aligned precisely to be consistent with a fold or 3-d corner. the amount of perceived depth is graded, depending on the steepness and the density of angles in the aligned-angle pattern. the required precision of the alignment implies that early retinotopic visual cortical areas may be involved in this perceptual behavior, but the linkage of form with perceived depth suggests involvement of higher cortical areas as well.”
Sundareswara, R.. (2008). Probabilistic inference in human and computer vision.. Dissertation Abstracts International: Section B: The Sciences and Engineering
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“This thesis aims to improve the understanding of 3-dimensional geometry from images as a statistical inference problem provides both new explanations for the origins of spontaneous perceptual switching in the human visual system, and new computer vision algorithms with lower 3d reconstruction errors. perceptual bistability refers to the phenomenon of spontaneous perceptual switching between two likely interpretations of a single image. although frequently explained by processes of adaptation or hysteresis, we show that perceptual switching can arise as a natural by-product of performing probabilistic (bayesian) inference, which interprets images by combining models of image formation with knowledge of scene regularities. we introduce a theoretical model consistent with bayesian models of vision that involves searching for good interpretations of an image by sampling a bimodal posterior distribution representing the two interpretations of a necker cube (a cuboidal wire frame object capable of eliciting two distinct percepts). this sampling scheme, coupled with a decay process that favors recent over old interpretations, is capable of producing data that resembles human bistable behavior. furthermore, we introduce psychophysical experiments that are equivalent to manipulating the prior probability influencing the interpretation of the necker cube. we show that human bistable switching behavior can be predicted with the equivalent manipulations of the theoretical model. to describe changes in the temporal dynamics of the perceptual alternations beyond traditional static measures like percept durations, we introduce markov renewal processes (mrps). mrps provide a general mathematical framework for describing probabilistic switching behavior in finite state processes. furthermore, we show the mrp is predicted by the bayesian model. because the bayesian model produces the same kind of stochastic process found in human perceptual behavior, we conclude that bistability may represent an unavoidable by-product of normal perceptual inference with ambiguous images. additionally, this thesis contributes to the computer vision applications of 3d reconstruction by using a bayesian approach to handling camera calibration error to improve the quality of object reconstruction, discounting the effect of viewpoint. this approach provides a statistically optimal reconstruction for which error from viewpoint has been minimized. (psycinfo database record (c) 2016 apa, all rig…”
Taddei-Ferretti, C., Radilova, J., Musio, C., Santillo, S., Cibelli, E., Cotugno, A., & Radil, T.. (2008). The effects of pattern shape, subliminal stimulation, and voluntary control on multistable visual perception. Brain Research
Plain numerical DOI: 10.1016/j.brainres.2008.04.064
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“Spontaneous figure reversal of ambiguous patterns was analyzed in humans. a) with necker-“cube”-like, or ‘drum’-like figures, having square or round shaped ‘front’ and ‘rear’ surfaces, and either large or small ‘depth’, the perceptual intervals corresponding to both interpretations of ‘drum’ were longer than those of ‘cube’; the perceived ‘depth’ of the figures was less relevant for reversal timing (inter-reversal intervals were only slightly longer for the ‘deeper’ figures). although the shape of ‘front’ and ‘rear’ surfaces is not a crucial geometrical feature for figure reversal, it did influence its timing. more, or longer information-processing steps should probably be needed for perceptual representations of curvilinear patterns in comparison with rectangular ones. the underlying neural mechanisms are probably located at a relatively peripheral level in the visual system. b) with a modified necker ‘cube’-like figure, having the two internal vertices coincident, and the long axis of the figure aligned horizontally, the effect of voluntary control on perception-reversal timing overcomes opposite effects due to either fixation-attention to pattern’s focal zones, or subliminal stimulation by the pattern’s biased versions, suggesting one or the other perception’s possibility, while it is enhanced by concordant imagery. voluntary control should intervene downward at a high-level processing, and should probably affect both a decision-making and a perception-stabilizing mechanism in the process of the pattern’s unconscious interpretation. results a and b are confronted with other results on both perceptual and binocular rivalry of up-to-date literature, in the frame of discussions on low-level bottom-up automatic stimulus-driven processing vs high-level top-down covert attention-driven processing. © 2008 elsevier b.v. all rights reserved.”
Pitts, M. A., Martínez, A., Stalmaster, C., Nerger, J. L., & Hillyard, S. A.. (2009). Neural generators of ERPs linked with Necker cube reversals. Psychophysiology
Plain numerical DOI: 10.1111/j.1469-8986.2009.00822.x
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“Multistable perception occurs when a single physical stimulus leads to two or more distinct percepts that spontaneously switch (reverse). previous erp studies have reported reversal negativities and late positive components associated with perceptual reversals. the goal of the current study was to localize the neural generators of the reversal erp components in order to evaluate their correspondence with previous fmri results and to better understand their functional significance. a necker-type stimulus was presented for brief intervals while subjects indicated their perceptions. local auto-regressive average source analyses and dipole modeling indicated that sources for the reversal negativity were located in inferior occipital-temporal cortex. generators of the late positive component were estimated to reside in inferior temporal and superior parietal regions.”
Kornmeier, J., & Bach, M.. (2009). Object perception: When our brain is impressed but we do not notice it. Journal of Vision
Plain numerical DOI: 10.1167/9.1.7
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“Although our eyes receive incomplete and ambiguous information, our perceptual system is usually able to successfully construct a stable representation of the world. in the case of ambiguous figures, however, perception is unstable, spontaneously alternating between equally possible outcomes. the present study compared eeg responses to ambiguous figures and their unambiguous variants. we found that slight figural changes, which turn ambiguous figures into unambiguous ones, lead to a dramatic difference in an erp (‘event-related potential’) component at around 400 ms. this result was obtained across two different categories of figures, namely the geometric necker cube stimulus and the semantic old/young woman face stimulus. our results fit well into the bayesian inference concept, which models the evaluation of a perceptual interpretation’s reliability for subsequent action planning. this process seems to be unconscious and the late eeg signature may be a correlate of the outcome.”
Arrighi, R., Arecchi, F. T., Farini, A., & Gheri, C.. (2009). Cueing the interpretation of a Necker Cube: A way to inspect fundamental cognitive processes. Cognitive Processing
Plain numerical DOI: 10.1007/s10339-008-0244-9
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“Covellite cus consists of alternating layers with compositions cus and cu2s2. we examine the anisotropy of the electrical conductivity and the origin of the structural phase transition in cus by performing extended hückel tight-binding band electronic structure calculations. our study shows that cus is a three-dimensional metal, but its conductivity should be much greater along the directions perpendicular than parallel to the c-axis. the partially empty valence bands of cus have strong contributions from the sulfur 3p orbitals of the cu2s2 layers, so that the oxidation state of cus is better described by (cu+)3(s2−)(s2− than by (cu+)3(s−)(s22−). the structural phase transition of cus is not driven by fermi surface instability. a probable cause for this phase transition cannot be the bonding interactions between the cu+ ions but the van der waals interactions of the s…s contacts between the cus and cu2s2 layers.”
Backus, B. T.. (2009). The Mixture of Bernoulli Experts: A theory to quantify reliance on cues in dichotomous perceptual decisions. Journal of Vision
Plain numerical DOI: 10.1167/9.1.6
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“The appearances of perceptually bistable stimuli can by definition be reported with confidence, so these stimuli may be useful to investigate how visual cues are learned and combined to construct visual appearance. however, interpreting experimental data (percent of trials seen one way or the other) requires a theoretically motivated measure of cue effectiveness. here we describe a simple bayesian theory for dichotomous perceptual decisions: the mixture of bernoulli experts or mbe. in this theory, a cue’s subjective reliability is the product of a weight and an estimate of the cue’s ecological validity. the theory (1) justifies the use of probit analysis to measure the system’s reliance on a cue and (2) enables hypothesis testing. to illustrate, we used apparent 3d rotation direction in perceptually ambiguous necker cube movies to test whether the visual system relied on a newly recruited cue (position of the stimulus within the visual field) to the same extent when a long-trusted cue (binocular disparity) was present or not present in the display. for six trainees, reliance on the newly recruited cue was similar whether or not the long-trusted cue was present, suggesting that the visual system assumed the new cue to be conditionally independent.”
Shannon, R., Jiang, Y., Bernat, E., Patrick, C., & He, S.. (2009). Genetic contribution to the rate of switching in bistable perception . Journal of Vision
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“Under normal viewing conditions, a person’s left and right eyes are presented with very similar visual input. when the input provided to the two eyes is so different that they cannot be combined into one coherent picture of visual space, input from each eye competes to be perceptually dominant over the other. such a perceptual competition is called binocular rivalry. the rate of perceptual switch seems to vary based on many extrinsic factors including the perceptual strength and context of the stimuli presented to the observer. however, when the stimulus conditions are fixed, the rate of switching is relatively stable for a given individual, but varies much more between individuals. despite extensive research on extrinsic factors that can influence rate of binocular rivalry switch, relatively little has been done to investigate intrinsic (individual biological differences) factors that may be involved. previous research has shown that factors such as bipolar disorder may slow binocular rivalry switch, indicating that intrinsic factors may be involved, however little information is available about the contribution of heritability to rivalry rates in normal populations. in the current study, rate-of-switch was recorded in a population of monozygotic and dizygotic twins under the same binocular rivalry conditions. rate-of-switch when viewing a bistable necker cube was also recorded for each subject. results suggest that there is a very strong heritability component related to switch rate in the case of binocular rivalry, but a much weaker genetic contribution to the switching rate of pictorial bistable images (necker cube).”
Britz, J., Britz, J., Landis, T., Landis, T., Michel, C. M., & Michel, C. M.. (2009). Right parietal brain activity precedes perceptual alternation of bistable stimuli.. Cerebral Cortex (New York, N.Y. : 1991)
Plain numerical DOI: 10.1093/cercor/bhn056
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“Momentary fluctuations of baseline activity have been shown to influence responses to sensory stimulation both behaviorally and neurophysiologically. this suggests that perceptual awareness does not solely arise from physical stimulus properties. here we studied whether the momentary state of the brain immediately before stimulus presentation indicates how a physically unique but perceptually ambiguous stimulus will be perceived. a complex necker cube was intermittently presented and subjects indicated whether their perception changed with respect to the preceding presentation. eeg was recorded from 256 channels. the prestimulus brain-state was defined as the spatial configuration of the scalp potential map within the 50 ms before stimulus arrival, representing the sum of all momentary ongoing brain processes. two maps were found that doubly dissociated perceptual reversals from perceptual stability. for eeg sweeps classified as either map, distributed inverse solutions were computed and statistically compared. this yielded activity confined to a region in right inferior parietal cortex that was significantly more active before a perceptual reversal. in contrast, no significant topographic differences of the evoked potentials elicited by stable vs. reversed necker cubes were found. this indicates that prestimulus activity in right inferior parietal cortex is associated with the perceptual change.”
Gregory, R. L.. (2009). Seeing through illusions. New York
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“(From the jacket) can we believe what we see with our own eyes? only up to a point, as the distinguished neuropsychologist richard gregory makes amply clear in this intriguing book. for we are constantly deceived. we rely on subtle clues, such as shading and strength of colour, to see depth, and on various assumptions about the natural world. illusions trick us with a dark shade here when we would expect a light one, or lines of equal length when surrounding clues suggest otherwise. it’s not (usually) the fault of our eyes, but our brains. what matters is not so much seeing as interpretation. and we interpret the world with brains that evolved to use vision to help us survive. that is why seeing arose at all. evolution has honed our brains to exploit the reflective and refractive qualities of objects in the sun’s light, and we rely on a number of innate assumptions of how the world works: we expect that this wall is in shadow, or that building looks small because it is far away. create an image that challenges these assumptions and we are misled. gregory draws together illusions familiar and less familiar, and divides them into classes based on the nature of the trickery involved—flipping ambiguity (for example, the necker cube), distortion, instability, and paradox among them. valuable as such a categorization is in itself, he uses the resulting ‘Peeriodictable’ to show how evolution has moulded our perception of the world. seeing, it becomes apparent, is not just a bottom-up process, from eye to brain. it also involves sideways and top-down processes reliant on implicit knowledge—an innate evolved syntax suited to our world, and a semantics based on innate perceptual knowledge—as well as our conceptual understanding, of what we know or think we know. how we interpret the world is profoundly moulded by the way in which our brains evolved, and coloured by what we have learned to see. (psycinfo database record (c) 2012 apa, all rights reserved)”
Troje, N.. (2009). Perceptual biases in biological motion perception and other depth-ambiguous stimuli. Brain and Cognition
Plain numerical DOI: 10.1167/10.7.792
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“
Biological motion stick-figures rendered orthographically and without self-occlusions do not contain any information about the order of their elements in depth and therefore are consistent with at least two different in-depth interpretations. interestingly, however, the visual system often prefers one over the other interpretation. in this study, we are investigating two different sources for such biases: the looking-from-above bias and the facing-the-viewer bias (vanrie et al. 2004). we measure perceived depth as a function of the azimuthal orientation of the walker, the camera elevation, and the walker’s gender, which have previously been reported to also affect the facing bias (brooks et al, 2008). we also compare dynamic walkers with static stick-figure displays. observers are required to determine whether 0.5 s presentations of stick-figures are rotating clockwise or counter-clockwise – basically telling us in that way which of the two possible in-depth interpretations they are perceiving. in contrast to previous work, this measure is entirely bias-free in itself. data collected with this method show that the facing-the-viewer bias is even stronger than previously reported and that it entirely dominates the viewing-from-above bias. effects of walker gender could not be confirmed. static figures which imply motion result in facing biases which are almost as strong as obtained for dynamic walker. the viewing-from-above bias becomes prominent for the profile views of walkers, for which the facing-the-viewer bias does not apply, and for other depth ambiguous stimuli (such as the necker cube). in all these cases, we find a very strong bias to interpret the 2d image in terms of a 3d scene as seen from above rather than from below. we discuss our results in the context of other work on depth ambiguous figures and look at differences between the initial percept as measured in our experiments and bistability observed during longer stimulus presentations.
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Charoenkitkarn, V., Kasemkitwattana, S., Therrien, B., Thosingha, O., & Vorapongsathorn, T.. (2009). Cognitive performance after a transiet ischemic attack: attention, working memory, and learning and memory. Thai Journal of Nursing Research
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“This prospective study aimed to explore the three main areas of cognitive function (attention; working memory; and, learning and memory) among individuals who had experienced a transient ischemic attack (tia). convenience sampling was used to recruit 52 individuals, who had experienced a tia, from outpatient and emergency departments in three tertiary hospitals, in bangkok, and one tertiary hospital in ayutthaya province, thailand; as well as 52 persons, who had experienced minor surgery and served as matched control subjects, from the outpatient department at a tertiary hospital in thailand. subjects were assessed, 3, 10 and 30 days after experiencing a tia or having minor surgery, using the necker cube pattern control test, trial making a test, digit span forward and backward test, barratt impulsiveness scale, irritability assessment scale, digit symbol substitution test, and hopkins verbal learning test. a repeated-measures-within-and-across-subjects design was used to analyze the results. findings indicate that those who had a tra continued to experience attention, working memory, and learning and memory changes, but not irritability changes, for over 30 days after symptom occurrence. three days after symptom occurrence, those who had a t/a showed less ability in the 3 main cognitive performances than did the control group. their performance ability became worse at day 10, but improved at day 30. all performances among those with a tia were lower than the control group, at all three time points. thus, nurses should be concerned about the cognitive ability of those who have had a tia, as well as their respective families, and provide information to both about the effects of a tia, particularly 10 days after symptom occurrence.”
Ernst, M. O., Di Luca, M., & Backus, B. T.. (2009). Recruitment of an invisible depth cue. In Journal of Vision
Plain numerical DOI: 10.1167/9.8.34
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“Cue recruitment occurs when a sensory signal is put into correlationnwith trusted cues and subsequently influences perceptual interpretationnas the trusted cues do. in all cue recruitment experiments to date,nthe signal has been well above detection threshold and was easilynvisible. for example, it has been shown that object position andnmotion can be recruited as a cue to influence the interpretationnof the ambiguous necker cube (haijiang et al., 2006). here we askednwhether a signal that is not visible on its own could be recruitednas a cue. vertical size ratio (vsr, the ratio of vertical anglesnsubtended by an object at the two eyes) is normally used to correctnfor relative position of the head when interpreting horizontal disparityn(gillam & lawergren, 1983; backus et al 1999) but it is notnvisible in displays consisting of horizontal lines only because therenare no horizontal discontinuities. we manipulated vsr of displaysnsimulating a cylinder composed of horizontal lines that rot atednabout a horizontal axis. on training trials, the rotation directionnof the cylinder was unambiguously specified by horizontal disparitynand occlusion cues and these trusted cues were correlated with thenvsr cue to be recruited. on test trials, the display did not containnhorizontal disparity or occlusion, so that the rotation directionnspecified by the trusted cues was ambiguous. if participants howevernmade use of the vsr cue in the test display rotation direction couldnbecome unambiguous after training. for 8 out of 9 participants, apparentnrotation on test trials became contingent on the value of vsr. wenconclude that a signal need not have perceptual consequences by itselfnfor the system to assign it a new use during the construction ofnappearances.”
Shen, L., Zeng, Z. L., Huang, P. Y., Li, Q., Mu, J., Huang, X. Q., … Xie, P.. (2009). Temporal cortex participates in spontaneous perceptual reversal. NeuroReport
Plain numerical DOI: 10.1097/WNR.0b013e32832974a8
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“The necker cube is perceived as two distinct three-dimensional forms; participants experience alternation between two mutually exclusive perceptions. perceptual dominance for one form tends to be maintained when the visual stimulus is intermittently removed. the effect is enhanced with the necker lattice (an array of necker cubes). neural processes underlying perceptual reversal and stabilization are unknown. functional mri was used to investigate the brain regions involved. regional activation differed between endogenous and stimulus-driven perceptual reversals, and between reversal and stabilization. our results indicated that the right anterior portion of superior temporal sulcus is likely to be involved in perceptual stabilization (perceptual memory), whereas reversal is modulated by destabilizing influences from the right frontal lobe.”
Alais, D., van Boxtel, J. J., Parker, A., & van Ee, R.. (2010). Attending to auditory signals slows visual alternations in binocular rivalry. Vision Research
Plain numerical DOI: 10.1016/j.visres.2010.03.010
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“A previous study has shown that diverting attention from binocular rivalry to a visual distractor task results in a slowing of rivalry alternation rate between simple orthogonal orientations. here, we investigate whether the slowing of visual perceptual alternations will occur when attention is diverted to an auditory distractor task, and we extend the investigation by testing this for two kinds of binocular rivalry stimuli and for the necker cube. our results show that doing the auditory attention task does indeed slow visual perceptual alternations, that the slowing effect is a graded function of attentional load, and that the attentional slowing effect is less pronounced for grating rivalry than for house/face rivalry and for the necker cube. these results are explained in terms of supramodal attentional resources modulating a high-level interpretative process in perceptual ambiguity, together with a role for feedback to early visual processes in the case of binocular rivalry. © 2010 elsevier ltd.”
Shimaoka, D., Kitajo, K., Kaneko, K., & Yamaguchi, Y.. (2010). Transient process of cortical activity during Necker cube perception: From local clusters to global synchrony. Nonlinear Biomedical Physics
Plain numerical DOI: 10.1186/1753-4631-4-S1-S7
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“BACKGROUND: it has been discussed that neural phase-synchrony across distant cortical areas (or global phase-synchrony) was correlated with various aspects of consciousness. the generating process of the synchrony, however, remains largely unknown. as a first step, we investigate transient process of global phase-synchrony, focusing on phase-synchronized clusters. we hypothesize that the phase-synchronized clusters are dynamically organized before global synchrony and clustering patterns depend on perceptual conditions.nnmethods: in an eeg study, kitajo reported that phase-synchrony across distant cortical areas was selectively enhanced by top-down attention around 4 hz in necker cube perception. here, we further analyzed the phase-synchronized clusters using hierarchical clustering which sequentially binds up the nearest electrodes based on similarity of phase locking between the cortical signals. first, we classified dominant components of the phase-synchronized clusters over time. we then investigated how the phase-synchronized clusters change with time, focusing on their size and spatial structure.nnresults: phase-locked clusters organized a stable spatial pattern common to the perceptual conditions. in addition, the phase-locked clusters were modulated transiently depending on the perceptual conditions and the time from the perceptual switch. when top-down attention succeeded in switching perception as subjects intended, independent clusters at frontal and occipital areas grew to connect with each other around the time of the perceptual switch. however, the clusters in the occipital and left parietal areas remained divided when top-down attention failed in switching perception. when no primary biases exist, the cluster in the occipital area grew to its maximum at the time of the perceptual switch within the occipital area.nnconclusions: our study confirmed the existence of stable phase-synchronized clusters. furthermore, these clusters were transiently connected with each other. the connecting pattern depended on subjects’ internal states. these results suggest that subjects’ attentional states are associated with distinct spatio-temporal patterns of the phase-locked clusters.”
Bertamini, M., Masala, L., Meyer, G., & Bruno, N.. (2010). Vision, haptics, and attention: New data from a multisensory necker cube. Perception
Plain numerical DOI: 10.1068/p6461
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“When looking monocularly at a three-dimensional (3-d) necker cube two percepts alternate: a cube and a truncated pyramid. the latter is due to a depth reversal. we studied the effect of haptic information by having participants hold the cube with their hands and explore two of its vertices. touch reduces the likelihood of the pyramid, consistent with a multisensory view of 3-d form perception. in addition, when the hand alternates between stationary and haptic exploration, the onset of the hand movement plays a crucial role in inhibiting reversals. a temporal analysis revealed that suppression occurred within a window lasting a few seconds from motion onset. in experiment 1, we monitored eye movements and instructed participants where to fixate. although the percept does depend on which vertex is fixated, we ruled out a role of changes of fixation as a mediating factor for the effect of motion onset. in experiment 2, we introduced a change of position of the exploring hand as a new type of transition. this type of change did not produce the same inhibition generated by the motion onset. we conclude that motion onset does not simply draw attention towards haptic information. rather, the influence of haptics peaks briefly after new information becomes available.”
van Dam, L. C. J., & Ernst, M. O.. (2010). Preexposure disrupts learning of location-contingent perceptual biases for ambiguous stimuli. Journal of Vision
Plain numerical DOI: 10.1167/10.8.15
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“The perception of a bistable stimulus as one or the other interpretation can be biased by prior presentations of that stimulus. such learning effects have been found to be long lasting even after small amounts of training. the effectiveness of training may be influenced by preexposure to the ambiguous stimulus. here we investigate the role of preexposure for learning a position-dependent perceptual bias. we used rotating necker cubes as the bistable stimuli, which were presented at two locations: above or below fixation. on training trials, additional depth cues disambiguated the rotation direction contingent on the location. on test trials, the rotating cube was presented without disambiguation cues. without preexposure to the ambiguous stimulus, subjects learned to perceive the cube to be rotating in the trained direction for both locations. however, subjects that were preexposed to the ambiguous stimulus did not learn the trained percept-location contingency, even though the preexposure was very short compared to the subsequent training. preexposure to the disambiguated stimulus did not interfere with learning. this indicates a fundamental difference between ambiguous test and disambiguated training trials for learning a perceptual bias. in short, small variations in paradigm can have huge effects for the learning of perceptual biases for ambiguous stimuli.”
Harrison, S., & Backus, B.. (2010). Disambiguating Necker cube rotation using a location cue: What types of spatial location signal can the visual system learn?. Journal of Vision
Plain numerical DOI: 10.1167/10.6.23
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“The direction of rotation of a wire-frame (necker) cube, which is perceptually bistable, can be trained to depend on stimulus location (q. haijiang, j. a. saunders, r. w. stone, & b. t. backus, 2006). however, it is not known which aspects of ‘location’ are important to this learning. we therefore explored ‘location’ in a series of experiments that separately assessed testing venue, location relative to the observer, and location in the retinal image as types of location signal that could potentially be recruited by the visual system. subjects were trained using wire-frame cubes with rotation direction disambiguated by depth cues. training cubes were presented at two locations, rotating in opposite directions. on interleaved test trials, ambiguous monocular cubes were presented at the same two locations. the extent to which test cubes were perceived to rotate according to the trained location-rotation contingency was our measure of location-cue recruitment. we found that only retinal position was recruited as a cue for apparent rotation direction. furthermore, the learned retinal location cue was robust to ocular transfer. our findings are consistent with a relatively low-level site of learning, such as mt.”
Iwayama, K., Takahashi, K., Watanabe, K., Hirata, Y., Aihara, K., & Suzuki, H.. (2010). Synchronized brain activity changes related to perceptual alternations. Artificial Life and Robotics
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“When we look at ambiguous figures, perception spontaneously changes from one to the other (perceptual alternation). we measured the brain activity from subjects who observed the necker cube, one of the most famous ambiguous figures, using magnetoencephalography (meg). to identify the brain activity inducing perceptual alternation, we propose a novel change-point detection method using spectral clustering to recurrence plots, and apply to measured data. synchronized activity changes were detected at parietal channels. © 2010 isarob.”
Mouri, C., & Chaudhuri, A.. (2010). The effect of stimulus interruptions on “fast switchers” and “slow switchers”: a neural model for bistable perception. Journal of Vision
Plain numerical DOI: 10.1167/10.7.339
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“Bistable perception is triggered by a physical stimulation that causes fluctuations between two perceptual interpretations. to date, no physiological mechanism has been causally linked to switching events (einhauser et al., 2008; hupe et al., 2008), leaving the neural basis of bistability unclear. external interruptions in the stimulus are known to affect perceptual switching rates: with long offsets, stimulus interruptions stabilize the percept, while short offsets trigger destabilization (noest et al., 2007). the current study explores the latter phenomenon in a necker cube presented for 600:1200 ms, 900:900 ms, and 1200:600 ms onset:offset durations. figure-ground contrast varied between 100%, 50%, 25%, and 12.5%. in the flashing conditions, a 100% contrast cube was presented during the ‘onset phase’, followed by a lower contrast cube during the ‘offset phase’. overall results indicate that destabilization occurs for flashing conditions, though individual results varied. in addition, subjects were evenly split between fast and slow switchers. slow switchers showed strong biases for one percept, and sensitivity to contrast manipulations. these results suggest a dichotomy between low-level rivalry, of orthogonal orientations for example (yu et al., 2002), and whole-form perception. similar patterns have been described in binocular rivalry (kovacs et al., 1996; lee & blake, 1999). previous research implicates experience (sakai et al., 1995) and genetic differences (shannon et al., 2009) to explain why certain individuals experience fast or slow perceptual switching. we discuss our results in the context of noisy neural competition (marr, 1982; moreno-bote et al., 2007). our neural model makes use of a dynamical system developed by wilson and cohen (wilson, 1999), in which two mutually inhibitory neurons interact. manipulation of input signal strengths yields broadly similar results to those observed in this psychophysical study, suggesting that input strengths at different levels of processing may explain the divergence between fast and slow switchers.”
Stoesz, B. M., & Jakobson, L. S.. (2010). Perceptual reversal patterns in individuals with Asperger Syndrome. Journal of Vision
Plain numerical DOI: 10.1167/9.8.478
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“When viewing ambiguous figures, individuals can exert selective attentional control over their perceptual reversals (e.g., struber & stadler, 1999). in the current study, we replicated this finding and also found that ambiguous figures containing faces are processed quite differently from those containing objects. viewers’ were able to divide their attention equally between the two face interpretations of boring’s young girl-old woman, and showed a face preference when viewing rubin’s vase-face. when instructed to alternate quickly between competing interpretations, their reversal rates were much quicker for these two figures than for figures containing only objects (maltese cross, necker cube), a finding that might reflect greater use of a holistic processing strategy when viewing figures involving faces. this was examined by comparing reversal behaviours for upright and inverted versions of rubin’s vase-face and looking for inversion effects (i.e., alterations in reversal behaviours associated with inversion). viewers spent more time perceiving the face than the vase interpretation with upright but not inverted stimuli, and made faster reversals with upright than inverted displays. these findings suggest that face inversion influences how we attend to faces, in addition to how we perceive and process them. describing the perceptual reversal patterns of individuals in the general population allowed us to draw comparisons to behaviours exhibited by individuals with asperger syndrome (as). the group data suggested that these individuals were less affected than neurotypical controls by figure type or stimulus inversion. examination of individual scores, moreover, revealed that the majority of participants with as showed atypical reversal patterns, particularly with ambiguous figures containing faces. the majority also showed an atypical rather than a diminished or absent inversion effect. together, our results show that ambiguous figures can be a valuable tool for examining face processing mechanisms in the general population and other distinct groups of individuals.”
Britz, J., Pitts, M. A., & Michel, C. M.. (2011). Right parietal brain activity precedes perceptual alternation during binocular rivalry. Human Brain Mapping
Plain numerical DOI: 10.1002/hbm.21117
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“Momentary fluctuations of baseline activity have been shown to influence responses to sensory stimulation both behaviorally and neurophysiologically. this suggests that perceptual awareness does not solely arise from physical stimulus properties. here we studied whether the momentary state of the brain immediately before stimulus presentation indicates how a physically unique but perceptually ambiguous stimulus will be perceived. a complex necker cube was intermittently presented and subjects indicated whether their perception changed with respect to the preceding presentation. {eeg} was recorded from 256 channels. the prestimulus brain-state was defined as the spatial configuration of the scalp potential map within the 50 ms before stimulus arrival, representing the sum of all momentary ongoing brain processes. two maps were found that doubly dissociated perceptual reversals from perceptual stability. for {eeg} sweeps classified as either map, distributed inverse solutions were computed and statistically compared. this yielded activity confined to a region in right inferior parietal cortex that was significantly more active before a perceptual reversal. in contrast, no significant topographic differences of the evoked potentials elicited by stable vs. reversed necker cubes were found. this indicates that prestimulus activity in right inferior parietal cortex is associated with the perceptual change.”
Nakatani, H., Orlandi, N., & Van Leeuwen, C.. (2011). Precisely timed oculomotor and parietal EEG activity in perceptual switching. Cognitive Neurodynamics
Plain numerical DOI: 10.1007/s11571-011-9168-7
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“Blinks and saccades cause transient interruptions of visual input. to investigate how such effects influence our perceptual state, we analyzed the time courses of blink and saccade rates in relation to perceptual switching in the necker cube. both time courses of blink and saccade rates showed peaks at different moments along the switching process. a peak in blinking rate appeared 1,000 ms prior to the switching responses. blinks occurring around this peak were associated with subsequent switching to the preferred interpretation of the necker cube. saccade rates showed a peak 150 ms prior to the switching response. the direction of saccades around this peak was predictive of the perceived orientation of the necker cube afterwards. peak blinks were followed and peak saccades were preceded by transient parietal theta band activity indicating the changing of the perceptual interpretation. precisely-timed blinks, therefore, can initiate perceptual switching, and precisely-timed saccades can facilitate an ongoing change of interpretation.”
McBain, R., Norton, D. J., Kim, J., & Chen, Y.. (2011). Reduced cognitive control of a visually bistable image in schizophrenia. Journal of the International Neuropsychological Society
Plain numerical DOI: 10.1017/S1355617711000245
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“Schizophrenia is associated with the inability to control and coordinate thoughts, actions, and perceptions. in conventional assessments of cognitive control, multiple sensory features of stimuli are concomitantly manipulated, introducing a confounding role of bottom-up perceptual information. to overcome this difficulty, we used an ambiguous visual stimulus (necker cube), which allowed measurement of cognitive control with constant sensory input. subjects (20 patients, 20 controls) were asked to control their perception of a transparent necker cube by keeping a designated plane at the front or back of the stimulus, the position of which is perceptually bistable. patients were highly deficient at controlling their perception of the cube. when a visual feature (the luminance contrast between a designated cube plane and the other planes) was systematically manipulated, an interaction was found whereby schizophrenia patients no longer under-performed on the highest contrast condition. these results show patients’ impairment of controlling perception in the absence of visual modulation and suggest the potential utility of perceptually based approaches to cognitive remediation in schizophrenia.”
Reichert, D. P., Seriès, P., & Storkey, A. J.. (2011). Neuronal Adaptation for Sampling-Based Probabilistic Inference in Perceptual Bistability. Advances in Neural Information Processing Systems
Plain numerical DOI: 10.1039/C4RA01625D
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“It has been argued that perceptual multistability reflects probabilistic inference performed by the brain when sensory input is ambiguous. alternatively, more traditional explanations of multistability refer to low-level mechanisms such as neuronal adaptation. we employ a deep boltzmann machine (dbm) model of cortical processing to demonstrate that these two different approaches can be com-bined in the same framework. based on recent developments in machine learn-ing, we show how neuronal adaptation can be understood as a mechanism that improves probabilistic, sampling-based inference. using the ambiguous necker cube image, we analyze the perceptual switching exhibited by the model. we also examine the influence of spatial attention, and explore how binocular rivalry can be modeled with the same approach. our work joins earlier studies in demonstrat-ing how the principles underlying dbms relate to cortical processing, and offers novel perspectives on the neural implementation of approximate probabilistic in-ference in the brain.”
Klapp, S. T., & Jagacinski, R. J.. (2011). Gestalt Principles in the Control of Motor Action. Psychological Bulletin
Plain numerical DOI: 10.1037/a0022361
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“We argue that 4 fundamental gestalt phenomena in perception apply to the control of motor action. first, a motor gestalt, like a perceptual gestalt, is holistic in the sense that it is processed as a single unit. this notion is consistent with reaction time results indicating that all gestures for a brief unit of action must be programmed prior to initiation of any part of the movement. additional reaction time results related to initiation of longer responses are consistent with processing in terms of a sequence of indivisible motor gestalts. some actions (e.g., many involving coordination of the hands) can be carried out effectively only if represented as a unitary gestalt. second, a perceptual gestalt is independent of specific sensory receptors, as evidenced by perceptual constancy. in a similar manner a motor gestalt can be represented independently of specific muscular effectors, thereby allowing motor constancy. third, just as a perceptual pattern (e.g., a necker cube) is exclusively structured into only 1 of its possible configurations at any moment in time, processing prior to action is limited to 1 motor gestalt. fourth, grouping in apparent motion leads to stream segregation in visual and auditory perception; this segregation is present in motor action and is dependent on the temporal rate. we discuss congruence of gestalt phenomena across perception and motor action (a) in relation to a unitary perceptual-motor code, (b) with respect to differences in the role of awareness, and (c) in conjunction with separate neural pathways for conscious perception and motor control.”
Harrison, S. J., Backus, B. T., & Jain, A.. (2011). Disambiguation of Necker cube rotation by monocular and binocular depth cues: Relative effectiveness for establishing long-term bias. Vision Research
Plain numerical DOI: 10.1016/j.visres.2011.02.011
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“The apparent direction of rotation of perceptually bistable wire-frame (necker) cubes can be conditioned to depend on retinal location by interleaving their presentation with cubes that are disambiguated by depth cues (haijiang, saunders, stone, & backus, 2006; harrison & backus, 2010a). the long-term nature of the learned bias is demonstrated by resistance to counter-conditioning on a consecutive day. in previous work, either binocular disparity and occlusion, or a combination of monocular depth cues that included occlusion, internal occlusion, haze, and depth-from-shading, were used to control the rotation direction of disambiguated cubes. here, we test the relative effectiveness of these two sets of depth cues in establishing the retinal location bias. both cue sets were highly effective in establishing a perceptual bias on day 1 as measured by the perceived rotation direction of ambiguous cubes. the effect of counter-conditioning on day 2, on perceptual outcome for ambiguous cubes, was independent of whether the cue set was the same or different as day 1. this invariance suggests that a common neural population instantiates the bias for rotation direction, regardless of the cue set used. however, in a further experiment where only disambiguated cubes were presented on day 1, perceptual outcome of ambiguous cubes during day 2 counter-conditioning showed that the monocular-only cue set was in fact more effective than disparity-plus-occlusion for causing long-term learning of the bias. these results can be reconciled if the conditioning effect of day 1 ambiguous trials in the first experiment is taken into account (harrison & backus, 2010b). we suggest that monocular disambiguation leads to stronger bias either because it more strongly activates a single neural population that is necessary for perceiving rotation, or because ambiguous stimuli engage cortical areas that are also engaged by monocularly disambiguated stimuli but not by disparity-disambiguated stimuli. © 2011 elsevier ltd.”
Shannon, R. W., Patrick, C. J., Jiang, Y., Bernat, E., & He, S.. (2011). Genes contribute to the switching dynamics of bistable perception. Journal of Vision
Plain numerical DOI: 10.1002/tcr.201200025
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“Ordinarily, the visual system provides an unambiguous representation of the world. however, at times alternative plausible interpretations of a given stimulus arise, resulting in a dynamic perceptual alternation of the differing interpretations, commonly referred to as bistable or rivalrous perception. recent research suggests that common neural mechanisms may be involved in the dynamics of very different types of bistable phenomena. further, evidence has emerged that genetic factors may be involved in determining the rate of switch for at least one form of bistable perception, known as binocular rivalry. the current study evaluated whether genetic factors contribute to the switching dynamics for distinctly different variants of bistable perception in the same participant sample. switching rates were recorded for mz and dz twin participants in two different bistable perception tasks, binocular rivalry and the necker cube. strong concordance in switching rates across both tasks was evident for mz but not dz twins, indicating that genetic factors indeed contribute to the dynamics of multiple forms of bistable perception.”
de Lussanet, M. H. E., & Lappe, M.. (2011). Bistable alternation of point-light biological motion. Cogn. Dynamics
Plain numerical DOI: 10.1007/978-90-481-9695-1_66
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“The facing-in-depth of point-light biological motion is ambiguous: the frontal and back view look the same. however, since earlier studies found a very strong perceptual bias in point-light biological mtion, it is unknown whether it evokes an alternating (bistable) percept. in the present study, naive, untrained observers viewed point-light stimuli in half-profile view. all participants experienced spontaneous flipping of the orientation-in-depth, both for biological motion and necker cube displays. the number of perceptual flips was lower for the rocking cube than for the static one; and higher for biological motion than for rocking cubes. contrary to earlier findings the participants did not have a perceptual bias. we conclude that ambiguous biological motion does evoke a bistable percept. ”
Oh, S.. (2011). The eyeglass reversal. Attention, Perception, and Psychophysics
Plain numerical DOI: 10.3758/s13414-011-0116-8
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“Some figures, such as the necker cube, are spontaneously reversible between alternative percepts. before learning those skilled reversals, how do people achieve reversals for the very first time? it has been known that, in the case of a first reversal, people can be expected to see the reversal when given specific information about how the figures are ambiguous. this point was confirmed by using drawing versions of reversible figures. to demonstrate how intention plays a role in the initial reversal of a real object, a pair of regular eyeglasses, reversible in perspective, were presented to naïve observers in monocular vision. when the eyeglasses were viewed inwardly and the observers were given information that the eyeglasses could be ambiguous, they were able to easily see the reversal. when the eyeglasses were viewed outwardly, observers saw it only after they had been informed of exactly what the two alternative percepts were.interestingly, many observers often mistakenly saw the inwardly viewed eyeglasses as placed outwardly from the beginning of the observation, while they saw the outwardly viewed eyeglasses correctly. taking these results together, for the first reversal of a real object, the specificity of intention varies with the ambiguity of the object.”
Vasko, F. J., & Storozhyshina, N.. (2011). Balancing a transportation problem: Is it really that simple?. OR Insight
Plain numerical DOI: 10.1057/ori.2011.6
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“To make the argument that all morality is essen- tially one thing, gray, young, and waytz employ a series of helpful analogies, portraying morality as a bull, an elephant, a dog, a necker cube, h2o, a uni- versity, an invisible triangle, and the grand canyon skywalk. this impressive metaphoric diversity illus- trates just howdifficult it is to fit something as rich and complex as human morality into a single characteri- zation. it also illustrates the authors’ vagueness about what exactly is being argued by ‘essence.’”
Koralus, P. E.. (2011). Semantics in philosophy and cognitive neuroscience: The Open Instruction Theory of attitude report sentences, descriptions, and the Necker cube. Dissertation Abstracts International: Section B: The Sciences and Engineering
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“The dissertation presents a theory of semantics and pragmatics for both language and vision. i focus on sentences including proper names, descriptions, and attitude report verbs, and on the necker cube. i propose the open instruction theory (oit), according to which the linguistic meaning of a sentence and the semantic contribution of visual feature detectors are identified, not with propositions or other standard proposals, but with instructions for the construction of mental models. these instructions leave open certain aspects of interpretation, in ways precisely delineated. the process that builds mental models makes an ‘inference to the best interpretation’—roughly the best guess at what the world is like consistent with the instructions. what mental models represent—readily described as structured propositions—corresponds to intuitions about ‘what we are told’ and ‘what we see.’ applied to language, oit dovetails with syntax, and, as i argue, better captures intuitions about asserted and presupposed content than alternatives. applied to the necker cube, oit is supported by neural and psychological data, implemented as a neural model and explains puzzling phenomena as the by-product of near-optimal vision. i argue that extant theories of proper names, descriptions, and attitude report verbs conflict with language acquisition data and syntactic constraints; and that extant models of the necker cube are neurophysiologically implausible and lack explanatory power. i present tests for visual and linguistic ambiguity and argue that attitude reports, descriptions, and the necker cube are not ambiguous in ways traditionally supposed. moreover, oit eschews a quantificational treatment of descriptions and avoids making ‘is’ ambiguous. oit describes a crucial role of ‘topicality’ in both vision and language. oit makes it possible to systematically address issues that cut across cognitive domains, such as the relationship between presupposition, questions and visual perception, as well as visual fiction. oit also suggests tentative conclusions about the nature of language. principles involved in utterance interpretation beyond syntax and principles resembling external merge appear common to perceptual systems. if any principle of language is fundamentally unique, it has to be a more powerful principle like internal merge—a principle expected if language is ‘optimal’. (psycinfo database record (c) 2012 apa, all rights reserved)”
Oleson, K. E., Keebler, J., & Colombo, G.. (2011). The effects of image resolution on an armored vehicle differentiation task. In Proceedings of the Human Factors and Ergonomics Society
Plain numerical DOI: 10.1177/1071181311551291
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“A b s t r a c t our brain continuously evaluates different perceptual interpretations of the available sensory data in order to en-able flexible updates of conscious experience. individuals’ perceptual flexibility can be assessed using ambiguous stimuli that cause our perception to continuously switch between two mutually exclusive interpretations. neural processes underlying perceptual switching are thought to involve the visual cortex, but also non-sensory brain circuits that have been implicated in cognitive processes, such as frontal and parietal regions. perceptual flexibil-ity varies strongly between individuals and has been related to dopaminergic neurotransmission. likewise, there is also considerable individual variability in tasks that require flexibility in cognition, and dopamine-dependent striato-frontal signals have been associated with processes promoting cognitive flexibility. given the anatomical and neurochemical similarities with regard to perceptual and cognitive flexibility, we here probed whether indi-vidual differences in perceptual flexibility during bistable perception are related to individual cognitive flexibility associated neural correlates. 126 healthy individuals performed rule-based task switching during functional magnetic resonance imaging (fmri) and reported perceptual switching during the viewing of a modified version of the necker cube. mean phase duration as measure of perceptual flexibility correlated with task-switching as-sociated activity in the right putamen as part of the basal ganglia. in addition, we found a tentative correlation between perceptual and cognitive flexibility. these results indicate that individual differences in cognitive flexi-bility and associated fronto-striatal processing contribute to differences in perceptual flexibility. our findings thus provide empirical support for the general notion of shared mechanisms between perception and cognition.”
Kornmeier, J., Pfaffle, M., & Bach, M.. (2011). Necker cube: Stimulus-related (low-level) and percept-related (high-level) EEG signatures early in occipital cortex. J Vis
Plain numerical DOI: 10.1167/11.9.12
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“During observation of an ambiguous necker cube, our percept changes spontaneously although the external stimulus does not. an eeg paradigm allowing time-resolved eeg measurement during endogenous perceptual reversals recently revealed a chain of erp correlates beginning with an early occipital positivity at around 130 ms (reversal positivity, ‘rp’). in order to better understand the functional role of this rp, we investigated its relation to the p100, which is spatiotemporally close, typically occurring 100 ms after onset of a visual stimulus at occipital electrodes. we compared the relation of the erp amplitudes to varying sizes of ambiguous necker cubes. the main results are: (1) the p100 amplitude increases monotonically with stimulus size but is independent of the participants’ percept. (2) the rp, in contrast, is percept-related and largely unaffected by stimulus size. (3) a similar pattern to rp was found for reaction times: they depend on the percept but not on stimulus size. we speculate that the p100 reflects processing of elementary visual features, while the rp is related to a processing conflict during 3d interpretation that precedes a reversal. the present results indicate that low-level visual processing (related to stimulus size) and (relative) high-level processing (related to perceptual reversal) occur in close spatial and temporal vicinity.”
Beyerlein, I. J., Mara, N. A., Bhattacharyya, D., Alexander, D. J., & Necker, C. T.. (2011). Texture evolution via combined slip and deformation twinning in rolled silver-copper cast eutectic nanocomposite. International Journal of Plasticity
Plain numerical DOI: 10.1016/j.ijplas.2010.05.007
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“In this work, a silver-copper (ag-cu) nanocomposite with 200 nm bilayer thickness and eutectic composition was rolled at room temperature and 200 °c to nominal reductions of 75% and higher. initially the material had a random texture and {1 1 1} bi-metal interface plane. x-ray diffraction measurements show that the ag and cu phases developed the same brass-type (or ’alloy-type’) rolling texture regardless of rolling reduction and temperature. transmission electron microscopy analyses of the nanostructures before and after rolling suggest that adjoining ag and cu layers maintained a cube-on-cube relationship but the interface plane changed after rolling. polycrystal plasticity simulations accounting for plastic slip and deformation twinning in each phase were carried out to explore many possible causes for the brass-type texture development: twinning via a volume effect or barrier effect, shockley partial slip, and confined layer slip. the results suggest that the observed texture evolution may be due to profuse twinning within both phases. maintaining the cube-on-cube relationship would then imply that neighboring ag and cu crystals twinned by the same variant and on a twin plane non-parallel to the original interface plane. explanations for this unusual possibility for cu are provided at the end based on the properties of the ag-cu interface. © 2010 elsevier ltd. all rights reserved.”
Ozaki, T. J., Sato, N., Kitajo, K., Someya, Y., Anami, K., Mizuhara, H., … Yamaguchi, Y.. (2012). Traveling EEG slow oscillation along the dorsal attention network initiates spontaneous perceptual switching. Cognitive Neurodynamics
Plain numerical DOI: 10.1007/s11571-012-9196-y
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“An ambiguous figure such as the necker cube causes spontaneous perceptual switching {(sps).} the mechanism of {sps} in multistable perception has not yet been determined. although early psychological studies suggested that {sps} may be caused by fatigue or satiation of orientation, the neural mechanism of {sps} is still unknown. functional magnetic resonance imaging {(fmri)} has shown that the dorsal attention network {(dan),} which mainly controls voluntary attention, is involved in bistable perception of the necker cube. to determine whether neural dynamics along the {dan} cause {sps,} we performed simultaneous electroencephalography {(eeg)} and {fmri} during an {sps} task with the necker cube, with every {sps} reported by pressing a button. this {eeg-fmri} integrated analysis showed that (a) {3-4 hz} spectral {eeg} power modulation at fronto-central, parietal, and centro-parietal electrode sites sequentially appeared from 750 to {350 ms} prior to the button press; and (b) activations correlating with the {eeg} modulation traveled along the {dan} from the frontal to the parietal regions. these findings suggest that slow oscillation initiates {sps} through global dynamics along the attentional system such as the {dan.}”
Graham, J., & Iyer, R.. (2012). The Unbearable Vagueness of “Essence”: Forty-Four Clarification Questions for Gray, Young, and Waytz. Psychological Inquiry
Plain numerical DOI: 10.1080/1047840X.2012.667767
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“To make the argument that all morality is essen- tially one thing, gray, young, and waytz employ a series of helpful analogies, portraying morality as a bull, an elephant, a dog, a necker cube, h2o, a uni- versity, an invisible triangle, and the grand canyon skywalk. this impressive metaphoric diversity illus- trates just howdifficult it is to fit something as rich and complex as human morality into a single characteri- zation. it also illustrates the authors’ vagueness about what exactly is being argued by ‘essence.’”
Erkelens, C. J.. (2012). Contribution of disparity to the perception of 3D shape as revealed by bistability of stereoscopic necker Cubes. Seeing and Perceiving
Plain numerical DOI: 10.1163/18784763-00002396
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“The necker cube is a famous demonstration of ambiguity in visual perception of 3d shape. its bistability is attributed to indecisiveness because monocular cues do not allow the observer to infer one particular 3d shape from the 2d image a remarkable but not appreciated observation is that necker cubes are bistable during binocular viewing one would expect disparity information to veto bistability. to investigate the effect of zero and non-zero disparity on perceptual bistability in detail, perceptual dominance durations were measured for luminance- and disparity-defined necker cubes luminance-defined necker cubes were bistable for all tested disparities between the front and back faces of the cubes. absence of an effect of disparity on dominance durations suggested the suppression of disparity information judgments of depth between the front and back sides of the necker cubes, however, showed that disparity affected perceived depth. disparity-defined necker cubes were also bistable but dominance durations showed different distributions i propose a framework for 3d shape perception in which 3d shape is inferred from pictorial cues acting on luminance- and disparity-defined 2d shapes. (psycinfo database record (c) 2016 apa, all rights reserved)”
Van Elk, M., & Blanke, O.. (2012). Balancing bistable perception during self-motion. Experimental Brain Research
Plain numerical DOI: 10.1007/s00221-012-3209-2
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“In two experiments we investigated whether bistable visual perception is influenced by passive own body displacements due to vestibular stimulation. for this we passively rotated our participants around the vertical (yaw) axis while observing different rotating bistable stimuli (bodily or non-bodily) with different ambiguous motion directions. based on previous work on multimodal effects on bistable perception, we hypothesized that vestibular stimulation should alter bistable perception and that the effects should differ for bodily versus non-bodily stimuli. in the first experiment, it was found that the rotation bias (i.e., the difference between the percentage of time that a cw or ccw rotation was perceived) was selectively modulated by vestibular stimulation: the perceived duration of the bodily stimuli was longer for the rotation direction congruent with the subject’s own body rotation, whereas the opposite was true for the non-bodily stimulus (necker cube). the results found in the second experiment extend the findings from the first experiment and show that these vestibular effects on bistable perception only occur when the axis of rotation of the bodily stimulus matches the axis of passive own body rotation. these findings indicate that the effect of vestibular stimulation on the rotation bias depends on the stimulus that is presented and the rotation axis of the stimulus. although most studies on vestibular processing have traditionally focused on multisensory signal integration for posture, balance, and heading direction, the present data show that vestibular self-motion influences the perception of bistable bodily stimuli revealing the importance of vestibular mechanisms for visual consciousness.”
Gillett, G., & Liu, S. C.. (2012). Free will and Necker’s cube: Reason, language and top-down control in cognitive neuroscience. Philosophy
Plain numerical DOI: 10.1017/S003181911100057X
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“The debates about human free will are traditionally the concern of metaphysics but neuroscientists have recently entered the field arguing that acts of the will are determined by brain events themselves causal products of other events. we examine that claim through the example of free or voluntary switch of perception in relation to the necker cube. when i am asked to see the cube in one way, i decide whether i will follow the command (or do as i am asked) using skills that reason and language give to me and change my brain states accordingly. the voluntary shift of perspective in seeing the necker cube this way or that exemplifies the top-down control exercised by a human being on the basis of the role of language and meaning in their activity. it also indicates the lived story that is at the centre of each human consciousness. in the third part of this essay, three arguments are used to undermine metaphysical objections to the very idea of top-down self control.”
Harrison, S. J., & Backus, B. T.. (2012). Associative learning of shape as a cue to appearance: A new demonstration of cue recruitment. Journal of Vision
Plain numerical DOI: 10.1167/12.3.15
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“The perceived rotation direction of a wire-frame necker cube at stimulus onset can be conditioned to be dependent on retinal location (b. t. backus & q. haijiang, 2007; s. j. harrison & b. t. backus, 2010a). this phenomenon was proposed to be an example of the visual system learning new cues to visual appearance, by adaptation in response to new experiences. here, we demonstrate recruitment of a new cue, object shape, for the appearance of rotating 3d objects. the cue was established by interleaving ambiguous and disambiguated instances of two shapes, cubes and spheres, at the same retinal location. disambiguated cubes and spheres rotated in opposite directions. a significant bias was consequently introduced in the resolution of ambiguity, whereby the proportions of ambiguous shapes perceived as rotating clockwise differed, in the direction predicted by their disambiguated counterparts. this finding suggests that training led the visual system to distinguish between the two shapes. the association of rotation direction and shape was only achieved when monocular depth cues were used to depict rotation in depth; shapes disambiguated by binocular disparity did not lead to recruitment of the shape cue. we speculate that this difference may be the consequence of a difference in the neural pathways by which the disambiguating cues act. this new instance of the cue recruitment effect opens possibilities for further generalization of the phenomenon.”
Wilson, A.. (2012). Multistable perception of art-science imagery. Leonardo
Plain numerical DOI: 10.1162/LEON_a_00282
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“How do artists, scientists and artist-scientists view images, and how does their cultural background affect their inter- pretation? the author proposes that artist-scientists may exhibit cultural multistability, akin to the perceptual multistability associ- ated with viewing visual illusions such as the necker cube. after carrying out a survey, the author suggests that all individuals may exhibit cultural multistabil- ity in response to a challenging image. the author postulates a tendency of artist-scientists to use textural descriptions and discusses coming to see her own images in a new light.”
Clément, G., & Demel, M.. (2012). Perceptual reversal of bi-stable figures in microgravity and hypergravity during parabolic flight. Neuroscience Letters
Plain numerical DOI: 10.1016/j.neulet.2011.12.006
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“This experiment investigated whether the perception of depth-reversible figures is altered when the observer is in microgravity or hypergravity. a set of five bi-stable ambiguous figures was presented to ten participants in 1. g, 0. g, and 1.8. g during parabolic flight. the figures included static images such as the necker cube; kinetic depth displays such as a moving plaid and a sphere cluster of moving dots appearing to rotate in one of two directions; and a silhouette photograph. for each stimulus figure, subjects reported which of the two possible perceptual configurations they saw first and then continuously indicated when perceptual reversals occurred for durations ranging from 20 to 30. s. the same first percept was reported in 1. g, 0. g, and 1.8. g. the time delay for the first reversal between the two possible image interpretations was longer and the number of reversals was fewer in 0. g as compared to 1. g for four of the five figures. the opposite effects were seen when going from 0. g to 1.8. g. these findings confirm that, consistent with a multisensory approach to three-dimensional form perception, gravity has a clear effect on the interpretation of depth-based stimuli and this gravity-based component interferes with visual perception stability. © 2011 elsevier ireland ltd.”
Kawano, N., Iwamoto, K., Ebe, K., Aleksic, B., Noda, A., Umegaki, H., … Ozaki, N.. (2012). Slower adaptation to driving simulator and simulator sickness in older adults. Aging – Clinical and Experimental Research
Plain numerical DOI: 10.1007/BF03325260
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“Background and aims: methods of assessing driving abilities in the elderly are urgently needed. although the driving simulator (ds) appears to be a safe and cost-effective method of objectively evaluating driving performance, it may pose adaptation problems for elderly adults. in this study, we examined age-related adaptation deficits on the ds. methods: healthy young adults (n=15) and healthy elderly persons (n=17) completed some neuropsychological tests, and then performed a road-tracking task with the ds, which was repeated four times (trials 1-4). results: after simulated driving in ds, simulator sickness (ss) was observed in 18.8% of participants. the frequency of ss was 29.4% in elderly adults and 6.7% in young adults, and 17.6% of the elderly participants dropped out of the experiment. performance on the necker cube copying task was significantly correlated with the onset of ss. driving performance also showed a significant interaction between group and trial, for both driving accuracy and vehicle speed. in addition, the performance of elderly adults significantly improved between trials 1 and 4, reaching a plateau in trial 4, whereas that of young adults did not change across trials. conclusion: this study provides preliminary evidence of slower adaptation to a ds-based driving task by older adults, which was associated with cognitive aging. age affected driving accuracy and velocity when a road-tracking task was simply repeated. it is concluded that the capacity of elderly people to adapt to ds environments should be taken into consideration when evaluating their performance on ds tasks. (aging clin exp res 2012; 24: 285-289) abstract from author (copyright of aging clinical & experimental research is the property of springer science & business media b.v. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder’s express written permission. however, users may print, download, or email articles for individual use. this abstract may be abridged. no warranty is given about the accuracy of the copy. users should refer to the original published version of the material for the full abstract.)”
Orlandi, N.. (2012). Visual switching: The Illusion of instantaneity and visual search. Review of Philosophy and Psychology
Plain numerical DOI: 10.1007/s13164-012-0098-z
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“Abstract this paper questions two prima facie plausible claims concerning switch- ing in the presence of ambiguous figures. the first is the claim that reversing is an instantaneous process. the second is the claim that the ability to reverse demonstrates the interpretive, inferential and constructive nature of visual processing. empirical studies show that optical and cerebral events related to switching protract in time in a way that clashes with its perceived instantaneity. the studies further suggest an alternative theory of reversing: according to such alternative, seeing the same thing in multiple ways is a matter of uncovering what is already present to the senses through visual search. our visual world is remarkably stable.we tend to see familiar objects and faces in just one way through time. there are images, however, that defy this stability. looking at the necker cube, for example, may cause one to first see the cube oriented in a certain way and then to see it oriented differently. the switch between these two ways of seeing the cube seems to be instantaneous and to be due to the interpretative, constructive and inferential nature of visual processing (churchland 1989; fodor 1984; gregory 1970; palmer 1999; rock 1983). this paper questions both of these stances on the phenomenon. it reports on a number of studies that indicate that switching is a process that protracts in time and that involves a number of optical and neurological events. the paper further suggests an alternative account of revers- ing: according to this alternative, moving from seeing an image in one way to seeing it differently is done by engaging in visual search, where attention is paid to different parts of a figure or object and different visual percepts are processed as a result. reversing does not involve interpreting or constructing. if there is any sense in which the visual system constructs the percept is that the system slowly finds out what is present to the senses and represents it. evidence in cognitive and developmental psychology that supports this view is reviewed.”
Sans, M.. (2012). ¿Qué es el Coaching? sus origenes, definición, distitas metodologías y principios básicos de un coach. Revista de Investigación 3 Ciencias
Plain numerical DOI: 10.1109/TBME.2006.883733
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“This paper explores global time frequency approaches to eeg data analysis with the wigner distribution function and the symmetric ambiguity function. the task chosen was to characterize the activity profile of eeg signals in sample frontal, central and occipital electrodes from human subjects, coincident with the perception of a reversal in the orientation of a bistable necker cube figure. the result of this analysis has implications for blind signal processing as the goal was to identify an unknown input source eliciting the observed eeg signals. the methods demonstrate an internally initiated eeg signal source not tied to a regularly anticipated external source. the results demonstrate the general applicability of the methods for a wide variety of neural and biological signals and systems. the findings can be summarized as the observation of high energy activity patterns in terms of significant dissimilarities in the waveform, both in time and frequency, in the frontal and occipital electrodes, approximately 200-600 ms prior to the appearance of the premotor potentials in the medial electrodes”
Wawrzyniak, P., & Korbel, P.. (2012). Application Programming Interface for accurate multi-source mobile user positioning system. In Forum Innowacji Młodych Badaczy
Plain numerical DOI: 10.1068/p5630
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“The nature of processes underlying our perception of reversible figures was examined through two experiments investigating the effects of prior exposure conditions on an observer’s report of figural reversal. in experiment 1, observers were adapted over several minutes to an unambiguous version of a rotating necker cube prior to the presentation of the standard ambiguous figure. results indicated that adaptation produced an immediate bias to perceive the ambiguous figure in the opposite configuration (ie reverse bias) and to reduce reports of reversal over the test period. the introduction of a brief delay between the adaptation and test periods revealed that this bias is a highly transient effect and is only clearly evident when the adaptation and test figures are matched in size. in experiment 2, observers were primed with an unambiguous figure for a few seconds prior to the presentation of the standard ambiguous figure. in this case, the obtained bias strongly favored the observer’s reporting the ambiguous figure to be in the same configuration as the adapting figure (ie positive bias); and neither introducing a delay period nor changing figure size had any effect. we conclude that these experiments reveal the distinct roles of transient, retinally localized neural processes as well as more stable, global processes under specifiable conditions.”
Ludwig, K., Weilnhammer, V. A., Pastukhov, A., Sterzer, P., & Hesselmann, G.. (2012). Interocular suppression eliminates the processing of perceptual ambiguity. In European Conference on Visual Perception
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“Ambiguous visual stimuli are often used as a unique window on perception and consciousness. it remains unclear, however, whether conscious perception is a necessary prerequisite for the processing of ambiguity. to address this question, we tested whether an ambiguous stimulus, rendered invisible by interocular suppression (continuous flash suppression, cfs), affects the perception of subsequently presented visible ambiguous stimuli. in a 2×2 experimental design, a necker cube was presented either continuously or intermittently to one eye. cfs masks presented to the other eye were either present or absent. when present in the intermittent necker cube condition, the cfs masks were shown during the stimulus-off periods. in the continuous condition, cfs masks were shown during the same time intervals as in the intermittent condition while the necker cube was presented continuously. in this latter condition, the necker cube was thus constantly present but intermittently suppressed from awareness by cfs. as could be shown by comparing distributions of dominance times, the number of perceptual switches, and the probability of perceptual reappearance of the last dominant percept across conditions perception of the necker cube remained unaffected by periods of invisible stimulus presentation. this suggests that perceptual ambiguity is not processed during interocular suppression.”
Li, Q., Fleming, R. W., Logothetis, N. K., & Keliris, G. A.. (2012). Multi-Stable Visual Motion Perception. Frontiers in Computational Neuroscience
Plain numerical DOI: 10.3389/conf.fncom.2012.55.00058
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“Perceptual multi-stability is established when the brain fails to reach a single interpretation of the input from the external world. this issue intrigued scientific minds for more than two hundred years. this phenomenon has been found in vision (leopold & logothetis, 1999), audition (repp, 2007), olfaction (zhou & chen, 2009) and speech (warren & gregory, 1958). crucial features are similar within and across modalities (schwarts et al., 2012). in the visual modality, a number of ambiguous visual patterns have been described such as the necker cube, motion plaids, and binocular rivalry. multi-stable stimuli can provide unique insights into visual processing, as changes in perception are decoupled from changes in the stimulus. understanding of how multi-stable perception occurs might help one to understand visual perception in general. a key question in multi-stable perception is what the brain processes are responsible in the identification and alternation of the percepts. some investigators suggest that both top-down and bottom-up processes are involved (garcía pérez, 1989) but others argue that multi-stable perception does not need high-level processing but happens automatically as low-level competition between the stimulus features (akman et al., 2009; wilson et al, 2000). furthermore, it is well known that changes in stimulus features can bias perception in one or another direction, (klink, et al., 2012). in order to explore this question, we used multi-stable motion stimuli and specifically moving plaids consisting of three superimposed gratings moving in equidistant directions (difference of 120 deg). these stimuli induce the perception of component and pattern motion simultaneously since any two component gratings bind together and are perceived to move in the opposite direction of the third grating component. we modulated properties of the stimuli such as grating speed and size and recorded the responses of human subjects reporting the direction of the single grating using one of three buttons for each direction. preliminary results show that perceptual dominance is greatly affected by the selection of grating speeds. grating size did not greatly change the predominance of the different gratings. we find that gratings with speed closer to physiological values have greater probability to be perceived and that gratings with similar speeds tend to group more often than gratings with different speeds. further manipulations of other stimulus features…”
Sauer, S., Lemke, J., Wittmann, M., Kohls, N., Mochty, U., & Walach, H.. (2012). How long is now for mindfulness meditators?. Personality and Individual Differences
Plain numerical DOI: 10.1016/j.paid.2011.12.026
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“The experience of the present moment is characterized by an integrative mechanism that fuses successive events into a unitary phenomenological experience with a temporal limit of about 3. s. we hypothesized that proficiency of mindfulness expands the ability to stabilize an ambiguous percept in a bistable image paradigm using the necker cube, and that this effect is associated with individual differences in the level of mindfulness. expanded duration of nowness as indicated by the ability to stabilize a bistable image stimulus for a longer period of time may improve cognitive resources and thus be of practical interest. in a sample of n= 38 meditators and n= 38 non-meditators, meditators showed longer duration of subjective nowness. this effect was associated with individual mindfulness levels. it is concluded that the subjective now can be longer for meditators than for non-meditators, and individual levels of mindfulness may convey this effect. © 2012.”
Nakatani, H., & van Leeuwen, C.. (2013). Antecedent occipital alpha band activity predicts the impact of oculomotor events in perceptual switching. Frontiers in Systems Neuroscience
Plain numerical DOI: 10.3389/fnsys.2013.00019
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“Oculomotor events such as blinks and saccades transiently interrupt the visual input and, even though this mostly goes undetected, these brief interruptions could still influence the percept. in particular, both blinking and saccades facilitate switching in ambiguous figures such as the necker cube. to investigate the neural state antecedent to these oculomotor events during the perception of an ambiguous figure, we measured the human scalp electroencephalogram (eeg). when blinking led to perceptual switching, antecedent occipital alpha band activity exhibited a transient increase in amplitude. when a saccade led to switching, a series of transient increases and decreases in amplitude was observed in the antecedent occipital alpha band activity. our results suggest that the state of occipital alpha band activity predicts the impact of oculomotor events on the percept.”
O’Brien, C., Harris, M., & Higgs, S.. (2013). Effects of alcohol on attentional mechanisms involved in figure reversals. Human Psychopharmacology
Plain numerical DOI: 10.1002/hup.2337
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“Objective the impairing effects of alcohol on attention are well documented and are thought to involve inhibitory mechanisms. we used ambiguous figures (face-vase and necker cube) to test whether the intentional control mechanism is more vulnerable to the effects of alcohol than the automatic mechanism. method: participants were assigned to an alcohol (study 1, n=15; study 2, n=18), placebo (study 1, n=15; study 2, n=20) or control (study 1 only, n=10) group. the doses of alcohol were 0.8g/kg for men and 0.75g/kg for women. participants were shown the face-vase and necker cube figures and two variants of each, which were biased in varying degrees towards one interpretation. study 1 assessed the automatic control mechanism by asking participants to report spontaneous reversals. study 2 assessed the intentional control mechanism by asking participants to increase reversal rate. results: in study 1, reversal rate was similar for all groups, whereas in study 2, the alcohol group reported more reversals than the control group, although this was true only for the biased versions of the face-vase illusion. conclusions: the effect of alcohol on reversal rate is observed only during intentional reversals of semantically meaningful stimuli and only when the stimulus is biased. copyright (c) 2013 john wiley & sons, ltd.”
Corning, P. A.. (2013). Rotating the Necker cube: A bioeconomic approach to cooperation and the causal role of synergy in evolution. Journal of Bioeconomics
Plain numerical DOI: 10.1007/s10818-012-9142-4
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“The paradox of widespread cooperation in an intensely competitive natural world has been a major focus of theory and research in evolutionary biology and related disciplines over the past several decades. while much of the earlier work in this vein was gene-centered and grounded in inclusive fitness (or kin selection) theory, more recent developments suggest that it might also be useful to view cooperation (and biological complexity) from a bioeconomic perspective. here i will briefly explore the case for a paradigm shift, with special reference to the role of functional synergy as a distinct class of interdependent causal influences in evolution. i will argue that synergies of various kinds have been important drivers for cooperation in living systems at all levels. from this perspective, inclusive fitness and other factors may be enablers for cooperation, but the many exceptions show that genetic relatedness is neither necessary nor sufficient for the emergence of cooperative phenomena. [publication abstract]”
van Rooij, M. M. J. W.. (2013). Hysteresis in Processing of Perceptual Ambiguity on Three Different Timescales. Radboud Repository
Plain numerical DOI: 10.1063/1.3033202
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“Sensory information is a priori incomplete and ambiguous. our perceptual system has to make predictions about the sources of the sensory information, based on concepts from perceptual memory in order to create stable and reliable percepts. we presented ambiguous and disambiguated lattice stimuli (variants of the necker cube) in order to measure a hysteresis effects in visual perception. fifteen healthy participants observed two periods of ordered sequences of lattices with increasing and decreasing ambiguity and indicated their percepts, in two experimental conditions with different starting stimuli of the ordered sequence. we compared the stimulus parameters at the perceptual reversal between conditions and periods and found significant differences between conditions and periods, indicating memory contributions to perceptual outcomes on three different time scales from milliseconds over seconds up to lifetime memory. our results demonstrate the fruitful application of physical concepts like hysteresis and complementarity to visual perception.”
Hoshino, O.. (2013). Ambient GABA responsible for age-related changes in multistable perception. Neural Computation
Plain numerical DOI: 10.1162/NECO_a_00431
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“Multistable perception is a psychophysical phenomenon in which one unique interpretation alternates spontaneously every few seconds between two or more interpretations of the same sensory input. well-known examples include the necker cube and face-vase illusions in vision. interestingly, young adults generally see more perceptual switches than do elderly people. to understand the underlying neuronal mechanism of age-related multistable perception, we simulated a cortical neural network model that consists of multiple cell assemblies. in the network, a specific population of noncore cells and a common population of core cells form a cell assembly that represents a single object (or event). every dynamic cell assembly, activated by a given sensory input, involves the common (overlapping) population of core cells. ambient gaba-mediated intracortical tonic inhibition via extrasynaptic gabaa receptors destabilized the currently appearing dynamic cell assembly and terminated its burst firing. this allowed another dynamic cell assembly to emerge one after the other. namely, multistable perception took place. transporters, which were embedded in axon terminal membranes of interneurons, regulated levels of ambient gaba. for elderly people, we assumed a decline in transporter. this decelerated gaba augmentation and resulted in prolonging the durations of burst firing and thus in slowing perceptual switches. we suggest that poor control of ambient gaba levels due to age-related decline in gaba transporter may be responsible for the slowing of perceptual switches in elderly people.”
Shifu. (2013). string – n-grams in python, four, five, six grams? – Stack Overflow
Plain numerical DOI: 10.1097/WNR.0b013e32832974a8
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“The necker cube is perceived as two distinct three-dimensional forms; participants experience alternation between two mutually exclusive perceptions. perceptual dominance for one form tends to be maintained when the visual stimulus is intermittently removed. the effect is enhanced with the necker lattice (an array of necker cubes). neural processes underlying perceptual reversal and stabilization are unknown. functional mri was used to investigate the brain regions involved. regional activation differed between endogenous and stimulus-driven perceptual reversals, and between reversal and stabilization. our results indicated that the right anterior portion of superior temporal sulcus is likely to be involved in perceptual stabilization (perceptual memory), whereas reversal is modulated by destabilizing influences from the right frontal lobe.”
Zheng, M., & Ukai, K.. (2013). How intermittent presentation affects conscious perceptual reversals of ambiguous figures. SpringerPlus
Plain numerical DOI: 10.1186/2193-1801-2-180
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“Continually observing an ambiguous figure, we can perceive reversals between different interpretations. howrnperceptual reversals change when an ambiguous stimulus is presented intermittently? since no reversal can bernconsciously perceived duringrnoff-periodsrn, we use net average reversal interval (netari) but not usual averagernreversal interval to measure the perceptual reversal rate. netari is calculated by dividing accumulated time ofrnon-periodsrnby the number of reversals. the results are: (1) presenting an ambiguous figure intermittently increasedrnthe perceptual reversal rate; (2) the longer the exposure of necker cube, the slower the perceptual reversal raternwas, and whenrnon-periodsrnwere longer as 15 s, the perceptual reversal rate was slowed down and was almost samernto that in the continuous case; (3) the length ofrnoff-periodsrn(which ranged from 1 s to 5 s in the present study)rndid not affect the reversal rate.”
Hoon Lim, L., Chua, E., Mei Nyu, M., Ng, A., Shan, H., Ng, A., … Kandiah, N.. (2013). P4-174 NON-3D PATTERN OF COPYING THE NECKER CUBE AS A RISK OF DEMENTIA AMONG A NONDEMENTED POPULATION: REANALYSIS FROM THE TAJIRI PROJECT. Alzheimer’s & Dementia
Plain numerical DOI: 10.1016/j.jalz.2013.05.1566
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“Cerebral blood flow and altered cerebrovascular reactivity (cvr). methods: to determine changes in cerebral vascular reactivity in adults over 65 with mci -subcortical vascular (mci -vs) and without mci -vs.prospective, case-control. dcl-vs was defined for those subjects with memory com-plaints and objective cognitive impairment, detected by neuropsychological test. were obtained data and vascular risk factors. evaluation of cerebrovas-cular reactivity in middle cerebral arteries to hypercapnia was measured with transcranial doppler ultrasonography using the breath-holding index (bhi); pulsatility index (pi) was also recorded.was considered abnormal, an apnea index of<0.8%. we confirmed the normal distribution of bhi in both arteries, using the test kolmogororov -smirnov and shapiro-wills. results: we studied 60 subjects, 20 women and 10 men with mci -vs. in the control group, we studied 22 women and 8 men.average age 75 years (sd+/-5.01).the mean velocity of the right mca was 42.27 + /-12.6 cm /s in the case group and 58.7 + /-12.1cm/s in the control group p<0.005. the mean value of the speed of the left mca was 41.6 + /-12.6 cm -s in the case group vs 59.8 + /-10.8 cm /s in the control group p<0.005. the pulsatility index(pi) in patients with mci -vs was 1.02 in the right mca and 1.01 in the left mca. the cvr was altered in patients with mci -vs: .47% in right mca and .41%in left mca. vs the control group >0.8% (p <0.005). in ad-dition, we found a significant negative correlation between the values v’v’of cvr in the right mca with age, suggesting that at an older age, lower the cvr (r test, p<0.008). conclusions: the cerebral vascular reac-tivity, is impaired in subjects with vascular mci. likewise, we also observed a decrease in cvr withi ncreasing age,in both groups.this study shows that transcranial doppler can be a useful tool to confirm vascular cognitive profile.”
Shapiro, A., & Todorovic, D.. (2013). Oxford compendium of visual illusions. In Binocular rivalry: The illusion of disappearance
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“Specialized. previously issued in print: 2017. visual illusions are compelling phenomena that draw attention to the brain’s capacity to construct our perceptual world. this collection includes over 100 chapters on visual illusions, written by the illusions’ creators and vision scientists who have investigated mechanisms underlying their peculiarities. cover; the oxford compendium of visual illusions; copyright; contents; contributors; how to use the website; introduction; part i: introductory general chapters; 1. early history of illusions; 2. cross-cultural studies of illusions; 3. visual illusion in a comparative perspective; 4. an analysis of theoretical approaches to geometrical-optical illusions; 5. visual illusions in action; 6. motion illusions in man and machine; 7. the visual world as illusion: the ones we know and the ones we don’t; 8. visual illusions?; 9. why the concept of ‘visual illusions’ is misleading 10. where have all the illusions gone? a critique of the concept of illusionpart ii: geometrical; 11. weighted positional averaging in the illusions of the müller-lyer type; 12. the bar-cross-ellipse illusion; 13. the spinning ellipse speed illusion; 14. the ames window illusion and its variations; 15. three-dimensional müller-lyer illusion: theoretical and practical implications; 16. why do hills look so steep?; 17. ‘shape from smear’: an illusion of 3d shape, made by finger-painting with noise; 18. geometric-optical illusions under isoluminance? 19. the picture surface illusion: 3d biases 2d20. cast shadow illusions; 21. the leaning tower illusion; 22. the invisible saddle, or the cap-or-cup illusion; 23. symmetry and uprightness in visually perceived forms; 24. the bathtub illusion; 25. the pitchroom illusion: how high is up?; 26. geometric illusions in the human face and body; 27. dynamic illusory size contrast: enhanced relative size effects due to stimulus motion; 28. size contrast and assimilation in the delboeuf and ebbinghaus illusions; 29. the occlusion, configural shape, and shrinkage illusions 30. reverse-perspective art and objects-illusions in depth and motion31. the new moon illusion; 32. geometrical errors are the cost of maintaining the luminance contrast polarity; 33. antigravity slopes: a new type of visual illusion; 34. the geometrical-optical illusions of j. j. oppel; 35. oppel-kundt illusion; 36. the shifted-chessboard pattern as paradigm of the exegesis of geometrical-optical illusions; part iii: brightness/lightne…”
Wernery, J.. (2013). Bistable Perception of the Necker Cube in the Context of Cognition & Personality. Dissertation ETH Zurich
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“The necker cube is a bistable stimulus with a very long research history, spanning more than a century. very early, its temporal dynamics and its stimulus properties were examined. it was found that the number of reversals within a certain time interval were reproducible to a high accuracy within one observer but could vary significantly between different observers. already early in the first half of the 20th century, attempts at linking bistable perception of the necker cube with personality were made. even though much progress in the description of the reversal dynamics has been made since, a comprehensive understanding of inter-individual differences in bistable perception in terms personality traits and cognitive processes is still lacking today. two studies on neutral and voluntarily controlled perception of the necker cube were conducted. the temporal dynamics and its dependence on stimulus parameters as well as its relation to personality traits, mindfulness, temporal processing, working memory, general reaction times, attention and perception of an acoustic bistable stimulus were explored. new results on initial adaptation, goodness of fit and stationarity with respect to cube size were found. a quantitative analysis of a perceptual bias effect was given in terms of dwell time distributions. individual differences in voluntary control over perception of the necker cube were found to be related to personality traits and mindfulness. several personality traits not related to bistable perception and some related to its neutral perception were identified. furthermore, evidence for the presence of two mechanisms of temporal processing, namely processing speed and temporal integration, in bistable perception was discovered. similarities and differences between perception of the necker cube and a reversible word stimulus were reported. finally, individual differences in working memory capacity seem likely not to relate to bistable perception. in conclusion, an improved description of the temporal dynamics of bistable perception and some low-level modulating factors was given. furthermore, inter-individual differences in the dwell time distribution were shown to be reflected in several personality traits and cognitive processes, in particular time processing. this demonstrates that variations in bistable perception between individuals can indeed be better understood and classified by linking them to other characteristics in cognition and personality.”
Intaite, M., & Castelo-branco, M.. (2014). The linear impact of concurrent working memory load on dynamics of Necker cube perceptual reversals. Journal of Vision
Plain numerical DOI: 10.1167/14.1.13.doi
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“Ambiguous figures are visual stimuli that may be perceived in multistable interpretations. the role of attention in modulating perceptual reversals of ambiguous stimuli is not clear. we tested whether perceptual reversals depend on working memory by manipulating its load while the participants were viewing the necker cube. increasing working memory load delayed the latency and decreased the frequency of reversals. these effects followed a linear function of load. the findings imply shared resources of the mechanisms responsible for perceptual reversals and working memory maintenance. however, reversals were not completely abolished even with the hard seven- consonants load, suggesting that bottom-up processes continue to operate in the bistable perception dynamics when top-down mechanisms are attenuated. introduction”
Yokota, Y., Minami, T., Naruse, Y., & Nakauchi, S.. (2014). Neural processes in pseudo perceptual rivalry: An ERP and time-frequency approach. Neuroscience
Plain numerical DOI: 10.1016/j.neuroscience.2014.04.015
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“Necker cube is one of the ambiguous figures that is physically a static image but can be alternately perceived in two different perspectives. a great deal of debate exists regarding ambiguous figures that induce spontaneous switching between rival percepts. to investigate the time course of neural processes underlying such perceptual rivalry, we recorded electroencephalograms associated with participants’ perceptions of a necker cube under ambiguous and unambiguous conditions, using a modified discontinuous-presentation method. each condition consisted of two stimuli presented consecutively, starting with an unambiguous stimulus in both conditions. the second stimulus was either ambiguous (ambiguous condition) or unambiguous (control condition). we compared endogenous reversal activity of ambiguous stimuli with exogenous reversals. as a result, we found that the right-occipital beta-band activity (16-26. hz) increased 100-150. ms and 350-450. ms after the onset of the ambiguous stimulus only when the perception of the ambiguous stimulus differed from that of the first stimulus. these results indicate that activity in the right-occipital total beta band reflects endogenous switching between rivaling percepts. © 2014 ibro.”
Sonntag-Öström, E., Nordin, M., Lundell, Y., Dolling, A., Wiklund, U., Karlsson, M., … Slunga Järvholm, L.. (2014). Restorative effects of visits to urban and forest environments in patients with exhaustion disorder. Urban Forestry and Urban Greening
Plain numerical DOI: 10.1016/j.ufug.2013.12.007
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“This experimental study investigated differences in perceived restorativeness, mood, attention capacity and physiological reactions when visiting city and forest environments. twenty female patients diagnosed with exhaustion disorder visited three different forest environments and one city environment in randomized order. they performed a standardized 90-min test procedure in each of these environments. evaluation of the environments and psychological effects in mood were studied with self-administered questionnaires. attention capacity was studied with necker cube pattern control task. physiological responses were measured with regularly scheduled controls of heart rate and blood pressure, and a single test of heart rate recovery. visits to the forest environments were perceived as significantly more restorative, enhancing mood and attention capacity compared to the city. this also applies to the results of heart rate and to some extent to the results of the diastolic blood pressure. the results from this experimental study support our hypothesis that short visits to forest environments enhance both psychological and physiological recovery and that visits to forest environments are likely to be beneficial when suffering from exhaustion disorder. © 2014 elsevier gmbh.”
Harrison, S. J., & Backus, B. T.. (2014). A trained perceptual bias that lasts for weeks. Vision Research
Plain numerical DOI: 10.1016/j.visres.2014.03.001
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“Classical (pavlovian) conditioning procedures can be used to bias the appearance of physical stimuli. under natural conditions this form of perceptual learning could cause perception to become more accurate by changing prior belief to be in accord with what is statistically likely. however, for learning to be of functional significance, it must last until similar stimuli are encountered again. here, we used the apparent rotation direction of a revolving wire frame (necker) cube to test whether a learned perceptual bias is long lasting. apparent rotation direction was trained to have a different bias at two different retinal locations by interleaving the presentation of ambiguous cubes with presentation of cubes that were disambiguated by disparity and occlusion cues. four groups of eight subjects were subsequently tested either 1, 7, 14, or 28. days after initial training, respectively, using a counter-conditioning procedure. all four groups showed incomplete re-learning of the reversed contingency relationship during their second session. one group repeated the counter-conditioning and showed an increase in the reverse bias, showing that the first counter-conditioning session also had a long-lasting effect. the fact that the original learning was still evident four weeks after the initial training is consistent with the operation of a mechanism that ordinarily would improve the accuracy and efficiency of perception. © 2014 elsevier ltd.”
SCHROEDER, J.. (2014). Caverne Ou Grotte, Un Cube De Necker Géographique. Researchgate.Net
Plain numerical DOI: DOI 10.1007/s10439-009-9782-2
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“The objective of this study was to assess the effect of flow diversion by external carotid artery (eca) occlusion on ipsilateral regional cerebral blood flow (rcbf). local cerebral hyperperfusion in rats (n = 12) was induced by ligating the right eca. ipsilateral rcbf was determined pre- and post-ligation for 120 min using a laser doppler flow meter. sham animals (n = 6) were subjected to the craniotomy without ligation of the right eca. in a separate series of rats (n = 5), brain tissue oxygen levels (po(2)) in the right and left brain hemispheres were determined before and 90 min after ligation of the right eca using a tissue oxygenation monitoring unit. we investigated the effect of eca occlusion hemispheric changes in rcbf in one clinical case as a proof of concept. ligation of eca resulted in a statistically significant increase in rcbf on the ipsilateral side compared to the sham-operated rats (p < 0.0001). on average we observed a 34% increase (95% ci: 24-45%) in rcbf in the ipsilateral territory in the treated group compared with sham-operated rats. there was no significant variation in map for the treated animals. vascular permeability and cerebral water content in the right hemisphere after ligation of eca did not significantly differ from the contralateral hemisphere. ipsilateral hemisphere tissue po(2) was significantly higher compared to the contralateral area (p < 0.002) post-ligation or to the ipsilateral area (p < 0.001) prior to ligation. in the clinical case, occlusion of eca resulted in 3.6% and 12.1% increase in peak value and rise-time of the time-density curves. flow diversion by temporary occlusion of the eca can result in increased rcbf and cerebral po(2) on the ipsilateral side. the strategy may represent a viable option to augment rcbf in focal cerebral ischemia.”
Murphy, A. P., Leopold, D. A., & Welchman, A. E.. (2014). Perceptual memory drives learning of retinotopic biases for bistable stimuli. Frontiers in Psychology
Plain numerical DOI: 10.3389/fpsyg.2014.00060
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“The visual system exploits past experience at multiple timescales to resolve perceptualrn ambiguity in the retinal image. for example, perception of a bistable stimulus can bern biased towards one interpretation over another when preceded by a brief presentation of arn disambiguated version of the stimulus (positive priming) or through intermittentrn presentations of the ambiguous stimulus (stabilization). similarly, prior presentations ofrn unambiguous stimuli can be used to explicitly ‘train’ a long-lasting association betweenrn a percept and a retinal location (perceptual association). these phenonema have typicallyrn been regarded as independent processes, with short-term biases attributed to perceptualrn memory and longer-term biases described as associative learning. here we tested forrn interactions between these two forms of experience-dependent perceptual bias andrn demonstrate that short-term processes strongly influence long-term outcomes. we firstrn demonstrate that the establishment of long-term perceptual contingencies does not requirern explicit training by unambiguous stimuli, but can arise spontaneously during the periodicrn presentation of brief, ambiguous stimuli. using rotating necker cube stimuli, wern observed enduring, retinotopically specific perceptual biases that were expressed fromrn the outset and remained stable for up to forty minutes, consistent with the knownrn phenomenon of perceptual stabilization. further, bias was undiminished after a breakrn period of five minutes, but was readily reset by interposed periods of continuous, asrn opposed to periodic, ambiguous presentation. taken together, the results demonstrate thatrn perceptual biases can arise naturally and may principally reflect the brain’s tendency torn favor recent perceptual interpretation at a given retinal location. further, they suggest thatrn an association between retinal location and perceptual state, rather than a physical stimulus, is sufficient to generate long-term biases in perceptual organization.”
Kornmeier, J., & Bach, M.. (2014). EEG correlates of perceptual reversals in Boring’s ambiguous old/young woman stimulus. Perception
Plain numerical DOI: 10.1068/p7741
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“Ambiguous figures attract observers because perception alternates between different interpretations while the sensory information stays unchanged. understanding the underlying processes is difficult because the precise time instant of this endogenous reversal event needs to be known but�is difficult to measure. presenting ambiguous figures discontinuously and using stimulus onset as estimation of the reversal event increased temporal resolution and provided a series of well-confirmed eeg signatures. in the current eeg study we used this ‘onset paradigm’ for the first time with boring’s old/young woman stimulus. we found an early occipital event-related potential (erp) correlate of reversals between the perception of the old woman and the perception of the young woman that fits well with previous erp findings. this component was not followed by the often-reported occipito-parietal reversal negativity at 260�ms, but instead by an occipito-temporal n170, that is typically reported with face stimuli. we interpret our results as follows: ambiguity conflicts take place during processing of�stimulus elements in early visual areas roughly 130�ms after stimulus onset. the disambiguation�of these elements and their assembly to object ‘gestalts’ result from an interplay between early visual and object-specific brain areas in a temporal window between 130 and 260�ms after stimulus onset. in�the particular case of boring’s old/young woman the processes of element disambiguation and gestalt construction are already finished at 170�ms and, thus, 90�ms earlier than in the case of ambiguous geometric figures (eg�necker cube or schroeder staircase) or of binocular rivalrous gratings. keywords: multistable perception, bistable perception, perceptual ambiguity, onset paradigm, ambiguous figures, old/young woman, necker cube, eeg, erp, reversal positivity, reversal negativity”
Jain, A., Fuller, S., & Backus, B. T.. (2014). Cue-recruitment for extrinsic signals after training with low information stimuli. PLoS ONE
Plain numerical DOI: 10.1371/journal.pone.0096383
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“Cue-recruitment occurs when a previously ineffective signal comes to affect the perceptual appearance of a target object, in a manner similar to the trusted cues with which the signal was put into correlation during training. jain, fuller and backus reported that extrinsic signals, those not carried by the target object itself, were not recruited even after extensive training. however, recent studies have shown that training using weakened trusted cues can facilitate recruitment of intrinsic signals. the current study was designed to examine whether extrinsic signals can be recruited by putting them in correlation with weakened trusted cues. specifically, we tested whether an extrinsic visual signal, the rotary motion direction of an annulus of random dots, and an extrinsic auditory signal, direction of an auditory pitch glide, can be recruited as cues for the rotation direction of a necker cube. we found learning, albeit weak, for visual but not for auditory signals. these results extend the generality of the cue-recruitment phenomenon to an extrinsic signal and provide further evidence that the visual system learns to use new signals most quickly when other, long-trusted cues are unavailable or unreliable.”
Cao, Y., & Grossberg, S.. (2014). How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision. Frontiers in Psychology
Plain numerical DOI: 10.3389/fpsyg.2014.00694
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“The 3d laminart model of 3d vision and figure-ground perception is used to explain and simulate a key example of the venetian blind effect and to show how it is related to other well-known perceptual phenomena such as panum’s limiting case. the model proposes howlateral geniculate nucleus (lgn) and hierarchically organized laminar circuits in cortical areas v1, v2, and v4 interact to control processes of 3d boundary formation and surface filling-in that simulate many properties of 3d vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. interactions between layers 4, 3b, and 2/3 in v1 and v2 carry out stereopsis and 3d boundary formation. both binocular and monocular information combine to form 3d boundary and surface representations. surface contour surface-to-boundary feedback from v2 thin stripes to v2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3d boundaries, and triggering figure-ground perception. false binocular boundary matches are eliminated by gestalt grouping properties during boundary formation. in particular, a disparity filter, which helps to solve the correspondence problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area v2. the model has been used to simulate the consciously seen 3d surface percepts in 18 psychophysical experiments. these percepts include the venetian blind effect, panum’s limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da vinci stereopsis, and perceptual closure. these model mechanisms have also simulated properties of 3d neon color spreading, binocular rivalry, 3d necker cube, and many examples of 3d figure-ground separation.”
Liang, C. J., Li, Y., Lu, D. H., Chen, P., & Chen, T. T.. (2014). Improved target extraction algorithm for linear modulated stepped frequency signal. Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology
Plain numerical DOI: 10.1016/S0006-3223(00)01071-4
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“Background: a previous neural network simulation suggested that manicnstates arise from excessive levels of noise that destabilize neuralnrepresentations. the necker cube stick figure provides a simplenperceptual task that assesses stability of gestalt-type representations.nmethods: a neural network was developed that included a simulation ofnthe necker cube task. noise was added to induce maniclike jumps from onenrepresentation to another. a parallel study of necker cube perceptionnwas conducted with 16 patients diagnosed with manic-spectrum disorder 18npatients with schizophrenia, and 19 normal control subjects. cognitivenspeed and rate of indiscriminate responses were assessed using annauditory continuous performance task.nresults: during processing of the
Van Dalen, B. M.. (2014). Left ventricular ejection fraction by real-time three-dimensional echocardiography: The Necker cube for the naive realism of two-dimensional methods. Netherlands Heart Journal
Plain numerical DOI: 10.1007/s12471-014-0579-z
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Intaite, M., Koivisto, M., & Castelo-Branco, M.. (2014). Event-related potential responses to perceptual reversals are modulated by working memory load. Neuropsychologia
Plain numerical DOI: 10.1016/j.neuropsychologia.2014.02.016
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“While viewing ambiguous figures, such as the necker cube, the available perceptual interpretations alternate with one another. the role of higher level mechanisms in such reversals remains unclear. we tested whether perceptual reversals of discontinuously presented necker cube pairs depend on working memory resources by manipulating cognitive load while recording event-related potentials (erps). the erps showed early enhancements of negativity, which were obtained in response to the first cube approximately 500. ms before perceived reversals. we found that working memory load influenced reversal-related brain responses in response to the second cube over occipital areas at the 150-300. ms post-stimulus and over central areas at p3 time window (300-500. ms), suggesting that it modulates intermediate visual processes. interestingly, reversal rates remained unchanged by the working memory load. we propose that perceptual reversals in discontinuous presentation of ambiguous stimuli are governed by an early (well preceding pending reversals) mechanism, while the effects of load on the reversal related erps may reflect general top-down influences on visual processing, possibly mediated by the prefrontal cortex. © 2014 elsevier ltd.”
Pisarchik, A. N., Jaimes-Reátegui, R., Magallón-García, C. D. A., & Castillo-Morales, C. O.. (2014). Critical slowing down and noise-induced intermittency in bistable perception: Bifurcation analysis. Biological Cybernetics
Plain numerical DOI: 10.1007/s00422-014-0607-5
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“Stochastic dynamics and critical slowing down were studied experimentally and numerically near the onset of dynamical bistability in visual perception under the influence of noise. exploring the necker cube as the essential example of an ambiguous figure, and using its wire contrast as a control parameter, we measured dynamical hysteresis in two coexisting percepts as a function of both the velocity of the parameter change and the background luminance. the bifurcation analysis allowed us to estimate the level of cognitive noise inherent to brain neural cells activity, which induced intermittent switches between different perception states. the results of numerical simulations with a simple energy model are in good qualitative agreement with psychological experiments.”
Wernery, J., Atmanspacher, H., Kornmeier, J., Candia, V., Folkers, G., & Wittmann, M.. (2014). Temporal processing in bistable perception of the Necker cube. Perception
Plain numerical DOI: 10.1068/p7780
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“Perception of ambiguous figures is unstable and alternates repeatedly between possible interpretations. some approaches to explaining this phenomenon have, so far, assumed low-level bottom- up mechanisms like adaptation and mutual inhibition of underlying neural assemblies. in contrast, less precise top-down approaches assume high-level attentional control mechanisms generalised across sensory modalities. in the current work we focused on specific aspects of the top-down approach. in a first study we used dwell times (periods of transiently stable percepts) and the parameters of dwell time distribution functions to compare the dynamics of perceptual alternations between visual (necker cube) and auditory ambiguity (verbal transformation effect). in a second study we compared the endogenous alternation dynamics of the necker cube with parameters from two attention tasks with different regimes of temporal dynamics. the first attention task (d2) is characterised by endogenous self-paced dynamics, similar to the dynamics underlying perceptual alternations of ambiguous figures, and we found clear correlations between dwell time parameters (necker cube) and processing speed (d2 task). the temporal dynamics of the second (go/no-go) attention task, in contrast, are exogenously governed by the stimulus protocol, and we found no statistically significant correlation with the necker cube data. our results indicate that both perceptual instability and higher-level attentional tasks are linked to endogenous brain dynamics on a global coordinating level beyond sensory modalities.”
Baker, D. H., Karapanagiotidis, T., Coggan, D. D., Wailes-Newson, K., & Smallwood, J.. (2015). Brain networks underlying bistable perception. NeuroImage
Plain numerical DOI: 10.1016/j.neuroimage.2015.06.053
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“Bistable stimuli, such as the necker cube, demonstrate that experience can change in the absence of changes in the environment. such phenomena can be used to assess stimulus-independent aspects of conscious experience. the current study used resting state functional magnetic resonance imaging (rs-fmri) to index stimulus-independent changes in neural activity to understand the neural architecture that determines dominance durations during bistable perception (using binocular rivalry and necker cube stimuli). anterior regions of the superior parietal lobule (spl) exhibited robust connectivity with regions of primary sensorimotor cortex. the strength of this region’s connectivity with the striatum predicted shorter dominance durations during binocular rivalry, whereas its connectivity to pre-motor cortex predicted longer dominance durations for the necker cube. posterior regions of the spl, on the other hand, were coupled to associative cortex in the temporal and frontal lobes. the posterior spl’s connectivity to the temporal lobe predicted longer dominance during binocular rivalry. in conjunction with prior work, these data suggest that the anterior spl contributes to perceptual rivalry through the inhibition of incongruent bottom up information, whereas the posterior spl influences rivalry by supporting the current interpretation of a bistable stimulus. our data suggests that the functional connectivity of the spl with regions of sensory, motor, and associative cortex allows it to regulate the interpretation of the environment that forms the focus of conscious attention at a specific moment in time.”
Van Zyl, J. J., Cowley, A. A., Neveling, R., Buthelezi, E. Z., Förtsch, S. V., Mabiala, J., … Usman, I. T.. (2015). Incident-energy dependence of angular distributions of cross section and analyzing power for the Ni 58 (p-, He 3) Co 56 reaction between 80 and 120 MeV. Physical Review C – Nuclear Physics
Plain numerical DOI: 10.1103/PhysRevC.91.024614
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“When our visual system is confronted with ambiguous stimuli, the perceptual interpretation spontaneously alternates between the competing incompatible interpretations. the timing of such perceptual alternations is highly stochastic and the underlying neural mechanisms are poorly understood. we show that perceptual alternations can be triggered by a transient stimulus presented nearby. the induction was tested for four types of bistable stimuli: structure-from-motion, binocular rivalry, necker cube, and ambiguous apparent motion. while underlying mechanisms may vary among them, a transient flash induced time-locked perceptual alternations in all cases. the effect showed a dependence on the adaptation to the dominant percept prior to the presentation of a flash. these perceptual alternations show many similarities to perceptual disappearances induced by transient stimuli (kanai and kamitani, 2003 journal of cognitive neuroscience 15 664-672; moradi and shimojo, 2004 vision research 44 449-460). mechanisms linking these two transient-induced phenomena are discussed.”
Kogo, N., Hermans, L., Stuer, D., van Ee, R., & Wagemans, J.. (2015). Temporal dynamics of different cases of bi-stable figure-ground perception. Vision Research
Plain numerical DOI: 10.1016/j.visres.2014.10.029
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“Segmentation of a visual scene in ‘figure’ and ‘ground’ is essential for perception of the three-dimensional layout of a scene. in cases of bi-stable perception, two distinct figure-ground interpretations alternate over time. we were interested in the temporal dynamics of these alternations, in particular when the same image is presented repeatedly, with short blank periods in-between. surprisingly, we found that the intermittent presentation of rubin’s classical ‘face-or-vase’ figure, which is frequently taken as a standard case of bi-stable figure-ground perception, often evoked perceptual switches during the short presentations and stabilization was not prominent. interestingly, bi-stable perception of kanizsa’s anomalous transparency figure did strongly stabilize across blanks. we also found stabilization for the necker cube, which we used for comparison. the degree of stabilization (and the lack of it) varied across stimuli and across individuals. our results indicate, against common expectation, that the stabilization phenomenon cannot be generally evoked by intermittent presentation. we argue that top-down feedback factors such as familiarity, semantics, expectation, and perceptual bias contribute to the complex processes underlying the temporal dynamics of bi-stable figure-ground perception.”
Díaz-Santos, M., Cao, B., Mauro, S. A., Yazdanbakhsh, A., Neargarder, S., & Cronin-Golomb, A.. (2015). Effect of Visual Cues on the Resolution of Perceptual Ambiguity in Parkinson’s Disease and Normal Aging. Journal of the International Neuropsychological Society
Plain numerical DOI: 10.1017/S1355617715000065
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“
parkinson’s disease (pd) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. this raises the question of the extent to which these groups use visual cues when disambiguating information. twenty-seven individuals with pd, 23 normal control adults (nc), and 20 younger adults (ya) were presented a necker cube in which one face was highlighted by thickening the lines defining the face. the hypothesis was that the visual cues would help pd and nc to exert better control over bistable perception. there were three conditions, including passive viewing and two volitional-control conditions ( hold one percept in front; and switch: speed up the alternation between the two). in the hold condition, the cue was either consistent or inconsistent with task instructions. mean dominance durations (time spent on each percept) under passive viewing were comparable in pd and nc, and shorter in ya. pd and ya increased dominance durations in the hold cue-consistent condition relative to nc, meaning that appropriate cues helped pd but not nc hold one perceptual interpretation. by contrast, in the switch condition, nc and ya decreased dominance durations relative to pd, meaning that the use of cues helped nc but not pd in expediting the switch between percepts. provision of low-level cues has effects on volitional control in pd that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity. ( jins , 2015, 21 , 146–155)
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Erkelens, C.. (2015). Evidence for Obliqueness of Angles as a Cue to Planar Surface Slant Found in Extremely Simple Symmetrical Shapes. Symmetry
Plain numerical DOI: 10.3390/sym7010241
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“The necker cube is a striking example for perceptual dominance of 3d over 2d. object symmetry and obliqueness of angles are co-varying cues that may underlie the perceived slant of necker cubes. to investigate the power of the oblique-angle cue, slants were judged of extremely simple symmetrical shapes. slant computations based on an assumption of orthogonality were made for two abutting lines as a function of vertex angle and the slant of the screen. computed slants were compared with slants judged by six subjects under binocular viewing conditions. judged slant was highly correlated with slant specified by the oblique angles under an assumption of orthogonality. the contributions of screen cues, including binocular disparity, were negligible. the consistency of the judgments across subjects indicates the assumption of orthogonality as one of the principles underlying slant perception. necker cubes illustrate that the visual system can disengage unambiguous cues in favor of ambiguous object-symmetry and oblique-angle cues, if the latter indicate very different slants. selective disengagement of cues may be the mechanism that underlies the success of 2d images in ancient, as well as modern civilizations.”
Leptourgos, P., Notredame, C.-E., Jardri, R., & Denève, S.. (2015). Perceptual inferences in schizophrenia: A preliminary study on healthy participants. European Psychiatry
Plain numerical DOI: 10.1016/j.eurpsy.2015.09.216
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“Recently, jardri and denève proposed that positive symptoms in schizophrenia could be generated by an imbalance between excitation and inhibition in brain networks, which leads to circular inference, an aberrant form of inference where messages (bottom up and/or top down) are counted more than once and thus, are overweighted [1]. moreover, they postulated that psychotic symptoms are caused by a system that ‘expects what it senses’ and as a result attributes extreme weight even to weak sensory evidences. their hypothesis was then validated by a probabilistic inference task (in prep.). here, we put forward a new experimental study that could validate the circular inference framework in the domain of visual perception. initially, we restricted ourselves to healthy controls, whose tendencies for psychotic symptoms were measured using appropriate scales. we investigated the computations performed by perceptual systems when facing ambiguous sensory evidence. in those cases, perception is known to oscillate between two interpretations, a phenomenon known as bistable perception. more specifically, we asked how prior expectations and visual cues affect the dynamics of bistability. participants looked at a necker cube that was continuously displayed on the screen and reported their percept every time they heard a sound [2]. we manipulated sensory evidence by adding shades to the stimuli and prior expectations by giving different instructions concerning the presence of an implicit bias [3]. we showed that both prior expectations and visual cues significantly affect bistability, using both static and dynamic measures. we also found that the behavior could be well fitted by bayesian models (‘simple’ bayes, hierarchical bayesian model with markovian statistics). preliminary results from patients will also be presented.”
Díaz-Santos, M., Cao, B., Yazdanbakhsh, A., Norton, D. J., Neargarder, S., & Cronin-Golomb, A.. (2015). Perceptual, cognitive, and personality rigidity in Parkinson’s disease. Neuropsychologia
Plain numerical DOI: 10.1016/j.neuropsychologia.2015.01.044
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“Parkinson’s disease (pd) is associated with motor and non-motor rigidity symptoms (e.g., cognitive and personality). the question is raised as to whether rigidity in pd also extends to perception, and if so, whether perceptual, cognitive, and personality rigidities are correlated. bistable stimuli were presented to 28 non-demented individuals with pd and 26 normal control adults (nc). necker cube perception and binocular rivalry were examined during passive viewing, and the necker cube was additionally used for two volitional-control conditions: hold one percept in front, and switch between the two percepts. relative to passive viewing, pd were significantly less able than nc to reduce dominance durations in the switch condition, indicating perceptual rigidity. tests of cognitive flexibility and a personality questionnaire were administered to explore the association with perceptual rigidity. cognitive flexibility was not correlated with perceptual rigidity for either group. personality (novelty seeking) correlated with dominance durations on necker passive viewing for pd but not nc. the results indicate the presence in mild-moderate pd of perceptual rigidity and suggest shared neural substrates with novelty seeking, but functional divergence from those supporting cognitive flexibility. the possibility is raised that perceptual rigidity may be a harbinger of cognitive inflexibility later in the disease course.”
Oonuma, J., Kasai, M., Meguro, M., Akanuma, K., Yamaguchi, S., & Meguro, K.. (2016). Necker cube copying may not be appropriate as an examination of dementia: reanalysis from the Tajiri Project. Psychogeriatrics
Plain numerical DOI: 10.1111/psyg.12161
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“BACKGROUND: the necker cube is usually used for evaluating the visuoconstructional ability of patients with mild cognitive impairment (mci) and dementia. however, the necker cube is often considered a drawing with a visual illusionary perspective. the purpose of this study was to investigate whether necker cube copying could detect participants with mci due to dementia. methods: we retrospectively analyzed the database of the 1998 prevalence study that was part of the tajiri project (n = 599). pencil drawings of the necker cube on a4-sized white paper by non-demented people (clinical dementia rating (cdr) 0 and 0.5, n = 256) were classified into two patterns: non-three-dimension (3-d) and 3-d. two neuropsychologists assessed necker cube copying according to the criteria of the classification. after the classification, the database of the 2003 incidence study was used according to the subjects’ conversion to dementia. results: in the prevalence study, among those who made a non-3-d drawing of the necker cube, there were significantly fewer people in the cdr 0 group than in the cdr 0.5 and cdr 1+ groups; similarly, there were significantly fewer people in the cdr 0.5 group than in the cdr 1 + group (chi2 = 32.6, p < 0.001; post-hoc tests using chi2 tests, cdr 0 > cdr 0.5 > cdr 1+, p < 0.001). in the incidence study, among those who made a non-3-d drawing of the necker cube, there were significantly fewer people in the non-converter group than in the converter group (chi2 = 19.9, p < 0.001). however, there was no significant difference between the non-converter group (n = 21) and the converter group (n = 21) when age, sex, educational levels, and mini-mental state examination scores were controlled (chi2 = 0.0, p = 1.000). conclusions: our results suggested that necker cube copying may evaluate visual illusion as well as visuoconstructional ability. the necker cube may not be an appropriate test to detect participants with mci due to dementia.”
Ouhnana, M., & Kingdom, F. A. A.. (2016). Perceptual-binding in a rotating Necker cube: The effect of context motion and position. Vision Research
Plain numerical DOI: 10.1016/j.visres.2016.02.005
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“Previous studies have shown that spatial context influences the perceptual interpretation of ambiguous figures such as the necker cube; however, the properties that mediate the influences of an unambiguous spatial context have yet to be investigated. here we consider the effect of the motion and position of an unambiguous rotating skeleton cube on the perceived motion direction of an ambiguous rotating necker cube. we aimed to determine whether the motion of the two figures could be perceptually bound, and if it could, to determine the properties of the binding. we employed a novel procedure analogous to reverse correlation to establish the correlation between the rotation directions of the context and the perceived rotation directions of the target, across 32 s trial presentations. our results showed that changes in the rotation direction of the context triggered above-chance changes in the perceived rotation direction of the target. however, the relative speeds of rotation of the context and target had little effect on the correlations. position on the other hand had a significant effect: correlations were higher when the context was below compared to when above the target. our results reveal that change-synchrony not common fate is the factor mediating perceptual motion binding between the context and necker cube. we also suggest that prior knowledge of friction forces could underlie the position dependency of the context and necker-cube correlation.”
Sahlin, E., Lindegård, A., Hadzibajramovic, E., Grahn, P., Vega Matuszczyk, J., & Ahlborg, G.. (2016). The Influence of the Environment on Directed Attention, Blood Pressure and Heart Rate—An Experimental Study Using a Relaxation Intervention. Landscape Research
Plain numerical DOI: 10.1080/01426397.2014.982079
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“Attention is a basic cognitive function necessary in most daily activities. beneficial effects on cognitive abilities after exposure to nature have been reported. to explore if relaxation indoors and in nature differently affect directed attention and physiological measures, 51 participants (39 women) were measured on directed attention with the necker cube pattern control test before and after a guided progressive relaxation session indoors and outdoors in nature. additionally, systolic and diastolic blood pressure and heart rate were measured before and after the relaxation. participants’ environmental preference was explored. the main result showed an environmental effect on directed attention in favour of the natural environment. no similar environmental effect on physiological measures was seen. the results indicate that relaxation in natural environments had a positive effect on directed attention and hence could be an important component for preventive and rehabilitative interventions for stress-related symptoms.”
Satoh, M., Mori, C., Matsuda, K., Ueda, Y., Tabei, K. I., Kida, H., & Tomimoto, H.. (2016). Improved Necker Cube Drawing-Based Assessment Battery for Constructional Apraxia: The Mie Constructional Apraxia Scale (MCAS). Dementia and Geriatric Cognitive Disorders Extra
Plain numerical DOI: 10.1159/000449245
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“Background/aims: constructional apraxia (ca) is usually diagnosed by having patients draw figures; however, the reported assessments only evaluate the drawn figure. we designed a new assessment battery for ca (the mie constructional apraxia scale, mcas) which includes both the shape and drawing process, and investigated its utility against other assessment methods. methods: we designed the mcas, and evaluated inter-and intrarater reliability. we also investigated the sensitivity, specificity, and positive and negative predictive values in dementia patients, and compared mcas assessment with other reported batteries in the same subjects. results: moderate interrater reliability was shown for speech therapists with limited experience. moderate to substantial intrarater reliability was shown several weeks after initial assessment. when cutoff scores and times were set at 2/3 points and 39/40 s, sensitivity and specificity were 77.1 and 70.4%, respectively, with positive and negative predictive values of 80.0 and 66.7%, respectively. dementia patients had significantly worse scores and times for necker cube drawing than an elderly control group on the mcas, and on other assessments. conclusions: we conclude that the mcas, which includes both the assessment of the drawn necker cube shape and the drawing process, is useful for detecting even mild ca.copyright © 2016 the author(s) published by s. karger ag, basel.”
Sekutowicz, M., Schmack, K., Steimke, R., Paschke, L., Sterzer, P., Walter, H., & Stelzel, C.. (2016). Striatal activation as a neural link between cognitive and perceptual flexibility. NeuroImage
Plain numerical DOI: 10.1016/j.neuroimage.2016.07.046
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“Our brain continuously evaluates different perceptual interpretations of the available sensory data in order to enable flexible updates of conscious experience. individuals’ perceptual flexibility can be assessed using ambiguous stimuli that cause our perception to continuously switch between two mutually exclusive interpretations. neural processes underlying perceptual switching are thought to involve the visual cortex, but also non-sensory brain circuits that have been implicated in cognitive processes, such as frontal and parietal regions. perceptual flexibility varies strongly between individuals and has been related to dopaminergic neurotransmission. likewise, there is also considerable individual variability in tasks that require flexibility in cognition, and dopamine-dependent striato-frontal signals have been associated with processes promoting cognitive flexibility. given the anatomical and neurochemical similarities with regard to perceptual and cognitive flexibility, we here probed whether individual differences in perceptual flexibility during bistable perception are related to individual cognitive flexibility associated neural correlates. 126 healthy individuals performed rule-based task switching during functional magnetic resonance imaging (fmri) and reported perceptual switching during the viewing of a modified version of the necker cube. mean phase duration as measure of perceptual flexibility correlated with task-switching associated activity in the right putamen as part of the basal ganglia. in addition, we found a tentative correlation between perceptual and cognitive flexibility. these results indicate that individual differences in cognitive flexibility and associated fronto-striatal processing contribute to differences in perceptual flexibility. our findings thus provide empirical support for the general notion of shared mechanisms between perception and cognition.”
Intaitė, M., Duarte, J. V., & Castelo-Branco, M.. (2016). Working memory load influences perceptual ambiguity by competing for fronto-parietal attentional resources. Brain Research
Plain numerical DOI: 10.1016/j.brainres.2016.08.044
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“A visual stimulus is defined as ambiguous when observers perceive it as having at least two distinct and spontaneously alternating interpretations. neuroimaging studies suggest an involvement of a right fronto-parietal network regulating the balance between stable percepts and the triggering of alternative interpretations. as spontaneous perceptual reversals may occur even in the absence of attention to these stimuli, we investigated neural activity patterns in response to perceptual changes of ambiguous necker cube under different amounts of working memory load using a dual-task design. we hypothesized that the same regions that process working memory load are involved in perceptual switching and confirmed the prediction that perceptual reversals led to fmri responses that linearly depended on load. accordingly, posterior superior parietal lobule, anterior prefrontal and dorsolateral prefrontal cortices exhibited differential bold signal changes in response to perceptual reversals under working memory load. our results also suggest that the posterior superior parietal lobule may be directly involved in the emergence of perceptual reversals, given that it specifically reflects both perceptual versus real changes and load levels. the anterior prefrontal and dorsolateral prefrontal cortices, showing a significant interaction between reversal levels and load, might subserve a modulatory role in such reversals, in a mirror symmetric way: in the former activation is suppressed by the highest loads, and in the latter deactivation is reduced by highest loads, suggesting a more direct role of the apfc in reversal generation.”
Kornmeier, J., Wörner, R., & Bach, M.. (2016). Can I trust in what I see? EEG evidence for a cognitive evaluation of perceptual constructs. Psychophysiology
Plain numerical DOI: 10.1111/psyp.12702
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“Environmental information available to our senses is incomplete and to varying degrees ambiguous. it has to be disambiguated in order to construct stable and reliable percepts. ambiguous figures are artificial examples where perception is maximally unstable and alternates between possible interpretations. tiny low-level changes can disambiguate an ambiguous figure and thus stabilize percepts. the present study compares erps evoked by ambiguous stimuli and disambiguated stimulus variants across three visual categories: geometry (necker cube), motion (stroboscopic alternative motion stimulus, sam) and semantics (boring’s old/young woman). we found that (a) disambiguated stimulus variants cause stable percepts and evoke two huge positive erp excursions (cohen’s effect sizes 1–2), (b) the amplitudes of these erp effects are inversely related to the degree of stimulus ambiguity, and (c) this pattern of results is consistent across all three tested visual categories. this generality across visual categories points to mechanisms at a very abstract (cognitive) level of processing. we discuss our results in the context of a high-level bayesian inference unit that evaluates the reliability of perceptual processing results, given a priori incomplete, ambiguous sensory information. the erp components may reflect the outcome of this reliability estimation.”
Horiuchi, T., & Wesugi, S.. (2016). Interaction with the 3D Necker Cube and Its Depth Shift. In Proceedings – 2015 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2015
Plain numerical DOI: 10.1109/SMC.2015.262
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Arecchi, F. T., Farini, A., & Megna, N.. (2016). A test of multiple correlation temporal window characteristic of non-markov processes. European Physical Journal Plus
Plain numerical DOI: 10.1140/epjp/i2016-16050-6
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“We introduce a sensitive test of memory effects in successive events. the test consists of a combination k of binary correlations at successive times. k decays monotonically from k = 1 for uncorrelated events as a markov process. for a monotonic memory fading, k<1 always. here we report evidence of a k>1 temporal window in cognitive tasks consisting of the visual identification of the front face of the necker cube after a previous presentation of the same. we speculate that memory effects provide a temporal window with k>1 and this experiment could be a possible first step towards a better comprehension of this phenomenon. the k>1 behaviour is maximal at an inter-measurement time τ around 2s with inter-subject differences. the k>1 persists over a time window of 1s around tau$ ; outside this window the $k<1$ behaviour is recovered. the universal occurrence of a $ k>1$ window in pairs of successive perceptions suggests that, at variance with single visual stimuli eliciting a suitable response, a pair of stimuli shortly separated in time displays mutual correlations.”
Laukkonen, R. E., & Tangen, J. M.. (2017). Can observing a Necker cube make you more insightful?. Consciousness and Cognition
Plain numerical DOI: 10.1016/j.concog.2016.11.011
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“It is a compelling idea that an image as simple as a necker cube, or a duck-rabbit illusion, can reveal something about a person’s creativity. surprisingly, there are now multiple examples showing that people who are better at discovering ‘hidden’ images in a picture, are also better at solving some creative problems. although this idea goes back at least a century, little is known about how these two tasks—that seem so different on the surface—are related to each other. at least some forms of creativity (and indeed scientific discoveries) may require that we change our perspectives in order to discover a novel solution to a problem. it’s possible that such problems involve a similar cognitive process, and perhaps the same cognitive capacities, as switching perspectives in an ambiguous image. we begin by replicating previous work, and also show metacognitive similarities between the sudden appearance of hidden images in consciousness, and the sudden appearance of solutions to verbal insight problems. we then show that simply observing a necker cube can improve subsequent creative problem-solving and lead to more self-reported insights. we speculate that these results may in part be explained by conflict monitoring theory.”
Kornmeier, J., Wörner, R., Riedel, A., & Van Elst, L. T.. (2017). A different view on the necker cube—Differences in multistable perception dynamics between Asperger and non-Asperger observers. PLoS ONE
Plain numerical DOI: 10.1371/journal.pone.0189197
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Hramov, A. E., Maksimenko, V. A., Pchelintseva, S. V., Runnova, A. E., Grubov, V. V., Musatov, V. Y., … Pisarchik, A. N.. (2017). Classifying the perceptual interpretations of a bistable image using EEG and artificial neural networks. Frontiers in Neuroscience
Plain numerical DOI: 10.3389/fnins.2017.00674
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“© 2017 hramov, maksimenko, pchelintseva, runnova, grubov, musatov, zhuravlev, koronovskii and pisarchik. in order to classify different human brain states related to visual perception of ambiguous images, we use an artificial neural network (ann) to analyze multichannel eeg. the classifier built on the basis of a multilayer perceptron achieves up to 95% accuracy in classifying eeg patterns corresponding to two different interpretations of the necker cube. the important feature of our classifier is that trained on one subject it can be used for the classification of eeg traces of other subjects. this result suggests the existence of common features in the eeg structure associated with distinct interpretations of bistable objects. we firmly believe that the significance of our results is not limited to visual perception of the necker cube images; the proposed experimental approach and developed computational technique based on ann can also be applied to study and classify different brain states using neurophysiological data recordings. this may give new directions for future research in the field of cognitive and pathological brain activity, and for the development of brain-computer interfaces.”
Kurovskaya, M. K., Runnova, A. E., Zhuravlev, M. O., Grubov, V. V., Koronovskii, A. A., Pavlov, A. N., & Pisarchik, A. N.. (2017). Intermittency in electric brain activity in the perception of ambiguous images. In Proceedings of SPIE – The International Society for Optical Engineering
Plain numerical DOI: 10.1117/12.2267825
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“© 2016 spie. present paper is devoted to the study of intermittency during the perception of bistable necker cube image being a good example of an ambiguous object, with simultaneous measurement of eeg. distributions of time interval lengths corresponding to the left-oriented and right-oriented cube perception have been obtain. eeg data have been analyzed using continuous wavelet transform and it was shown that the destruction of alpha rhythm with accompanying generation of high frequency oscillations can serve as a marker of necker cube recognition process.”
Matsuda, T., Kitajo, K., Yamaguchi, Y., & Komaki, F.. (2017). A point process modeling approach for investigating the effect of online brain activity on perceptual switching. NeuroImage
Plain numerical DOI: 10.1016/j.neuroimage.2017.02.068
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“When watching an ambiguous figure that allows for multiple interpretations, our interpretation spontaneously switches between the possible options. such spontaneous switching is called perceptual switching and it is modulated by top-down selective attention. in this study, we propose a point process modeling approach for investigating the effects of online brain activity on perceptual switching, where we define online activity as continuous brain activity including spontaneous background and induced activities. specifically, we modeled perceptual switching during necker cube perception using electroencephalography (eeg) data. our method is based on the framework of point process model, which is a statistical model of a series of events. we regard perceptual switching phenomenon as a stochastic process and construct its model in a data-driven manner. we develop a model called the online activity regression model, which enables to determine whether online brain activity has excitatory or inhibitory effects on perceptual switching. by fitting online activity regression models to experimental data and applying the likelihood ratio testing with correction for multiple comparisons, we explore the brain regions and frequency bands with significant effects on perceptual switching. the results demonstrate that the modulation of online occipital alpha activity mediates the suppression of perceptual switching to the non-attended interpretation. thus, our method provides a dynamic description of the attentional process by naturally accounting for the entire time course of brain activity, which is difficult to resolve by focusing only on the brain activity around the time of perceptual switching.”
Piantoni, G., Romeijn, N., Gomez-Herrero, G., Van Der Werf, Y. D., & Van Someren, E. J. W.. (2017). Alpha power predicts persistence of bistable perception. Scientific Reports
Plain numerical DOI: 10.1038/s41598-017-05610-8
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“Perception is strongly affected by the intrinsic state of the brain, which controls the propensity to either maintain a particular perceptual interpretation or switch to another. to understand the mechanisms underlying the spontaneous drive of the brain to explore alternative interpretations of unchanging stimuli, we repeatedly recorded high-density eeg after normal sleep and after sleep deprivation while participants observed a necker cube image and reported the durations of the alternating representations of their bistable perception. we found that local alpha power around the parieto-occipital sulcus within the first second after the emergence of a perceptual representation predicted the fate of its duration. an experimentally induced increase in alpha power by means of sleep deprivation increased the average duration of individual representations. taken together, these findings show that high alpha power promotes the stability of a perceptual representation and suppresses switching to the alternative. the observations support the hypothesis that synchronization of alpha oscillations across a wide neuronal network promotes the maintenance and stabilization of its current perceptual representation. elevated alpha power could also be key to the poorly understood cognitive deficits, that typically accompany sleep deprivation, such as the loss of mental flexibility and lapses of responsiveness. an important feature of the perceptual system is its flexibility to process identical physical stimuli in different ways depending on the circumstances. it enables, for example, the maintenance of attention to stimulus proper-ties with expected reward and prevents interference from distracting aspects of the same stimulus. this flexibil-ity is highly dependent on and tightly controlled by ongoing brain activity 1, 2”
Díaz-Santos, M., Mauro, S., Cao, B., Yazdanbakhsh, A., Neargarder, S., & Cronin-Golomb, A.. (2017). Bistable perception in normal aging: perceptual reversibility and its relation to cognition. Aging, Neuropsychology, and Cognition
Plain numerical DOI: 10.1080/13825585.2016.1173646
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“The effects of age on the ability to resolve perceptual ambiguity are unknown, though it depends on frontoparietal attentional networks known to change with age. we presented the bistable necker cube to 24 middle-aged and oas (older adults; 56-78 years) and 20 yas (younger adults; 18-24 years) under passive-viewing and volitional control conditions: hold one cube percept and switch between cube percepts. during passive viewing, oas had longer dominance durations (time spent on each percept) than yas. in the hold condition, oas were less able than yas to increase dominance durations. in the switch condition, oas and yas did not differ in performance. dominance durations in either condition correlated with performance on tests of executive function mediated by the frontal lobes. eye movements (fixation deviations) did not differ between groups. these results suggest that oas’ reduced ability to hold a percept may arise from reduced selective attention. the lack of correlation of performance between hold and executive-function measures suggests at least a partial segregation of underlying mechanisms.”
Urakawa, T., Aragaki, T., & Araki, O.. (2017). Exogenously-driven perceptual alternation of a bistable image: From the perspective of the visual change detection process. Neuroscience Letters
Plain numerical DOI: 10.1016/j.neulet.2017.05.041
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“Based on the predictive coding framework, the present behavioral study focused on the automatic visual change detection process, which yields a concomitant prediction error, as one of the visual processes relevant to the exogenously-driven perceptual alternation of a bistable image. according to this perspective, we speculated that the automatic visual change detection process with an enhanced prediction error is relevant to the greater induction of exogenously-driven perceptual alternation and attempted to test this hypothesis. a modified version of the oddball paradigm was used based on previous electroencephalographic studies on visual change detection, in which the deviant and standard defined by the bar’s orientation were symmetrically presented around a continuously presented necker cube (a bistable image). by manipulating inter-stimulus intervals and the number of standard repetitions, we set three experimental blocks: hm, im, and lm blocks, in which the strength of the prediction error to the deviant relative to the standard was expected to gradually decrease in that order. the results obtained showed that the deviant significantly increased perceptual alternation of the necker cube over that by the standard from before to after the presentation of the deviant. furthermore, the differential proportion of the deviant relative to the standard significantly decreased from the hm block to the im and lm blocks. these results are consistent with our hypothesis, supporting the involvement of the automatic visual change detection process in the induction of exogenously-driven perceptual alternation.”
Maksimenko, V. A., Runnova, A. E., Zhuravlev, M. O., Makarov, V. V., Nedayvozov, V., Grubov, V. V., … Pisarchik, A. N.. (2017). Visual perception affected by motivation and alertness controlled by a noninvasive brain-computer interface. PLoS ONE
Plain numerical DOI: 10.1371/journal.pone.0188700
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“The influence of motivation and alertness on brain activity associated with visual perception was studied experimentally using the necker cube, which ambiguity was controlled by the contrast of its ribs. the wavelet analysis of recorded multichannel electroencephalograms (eeg) allowed us to distinguish two different scenarios while the brain processed the ambiguous stimulus. the first scenario is characterized by a particular destruction of alpha rhythm (8-12 hz) with a simultaneous increase in beta-wave activity (20-30 hz), whereas in the second scenario, the beta rhythm is not well pronounced while the alpha-wave energy remains unchanged. the experiments were carried out with a group of financially motivated subjects and another group of unpaid volunteers. it was found that the first scenario occurred mainly in the motivated group. this can be explained by the increased alertness of the motivated subjects. the prevalence of the first scenario was also observed in a group of subjects to whom images with higher ambiguity were presented. we believe that the revealed scenarios can occur not only during the perception of bistable images, but also in other perceptual tasks requiring decision making. the obtained results may have important applications for monitoring and controlling human alertness in situations which need substantial attention. on the base of the obtained results we built a brain-computer interface to estimate and control the degree of alertness in real time.”
Ouhnana, M., Jennings, B. J., & Kingdom, F. A. A.. (2017). Common contextual influences in ambiguous and rivalrous figures. PLoS ONE
Plain numerical DOI: 10.1371/journal.pone.0176842
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“Images that resist binocular fusion undergo alternating periods of dominance and suppression, similarly to ambiguous figures whose percepts alternate between two interpretations. it has been well documented that the perceptual interpretations of both rivalrous and ambiguous figures are influenced by their spatio-temporal context. here we consider whether an identical spatial context similarly influences the interpretation of a similar rivalrous and ambiguous figure. we developed a binocularly rivalrous stimulus whose perceptual experience mirrors that of a necker cube. we employed a paradigm similar to that of ouhnana and kingdom (2016) to correlate the magnitude of influence of context between the rivalrous and ambiguous target. our results showed that the magnitude of contextual influence is significantly correlated within observers between both binocularly rivalrous and ambiguous target figures. this points to a similar contextual-influence mechanism operating on a common mechanism underlying the perceptual instability in both ambiguous and rivalrous figures.”
S., P., & J., R.. (2017). Chaotic dynamics of sleep onset: Proof of inverted consciousness. Sleep Medicine
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“Introduction: the hallmark of sleep is partial disconnection from environment that parallels the inverted sensory and mental activities. our goal was to demonstrate that the re-focusing of consciousness from the outside world to internal model of the world (imw) is a non-linear process that may be evaluated with dynamical analysis of eye and limb movements in order to recreate a topological equivalent picture of the original behavior of pertinent complex neuronal network. in addition, we intended to show similarity in the mode of access to imw in sleep and wakefulness. materials and methods: to define state consistently with changes in consciousness, 10 subjects, 10 asymptomatic patients and 4 patients with narcolepsy were instructed to squeeze a bulb connected with pressure sensor (eyes closed). 35-channel polysomnogram was digitally recorded, and 30 data files were created from the tracing of eye movement (em) and bulb pressure (bp) using edf to ascii converter (stationary time series of 7,500-15,000 /em) and 25,000-142,000 /bp/ data points, no filters). we used visual recurrence analysis software (vra; kononov, 2011) to compute embedding dimensions and time delays employing the false nearest neighbors method and average mutual information methods, respectively. the recurrence plots, correlation dimensions (cd) and phasespace charts were produced and analyzed in context of dynamics of eeg and subjective experience. results: mind-wandering and dreaming associated with alteration of motor and eye movement activities that was consistent with low dimensional chaotic dynamics across the continuum of drowsiness and light nrem sleep. unexpectedly, in rem sleep our patients with narcolepsy also were able to squeeze the bulb that permitted determination of chaotic dynamic with cd 1.15 ± 0.129. the striking similarity was found with dynamics of necker cube interpretation (cd 1.16 ± 0.12) when the same subjects squeezed a bulb in response of subjective changes of position of the cube. the most frequent dynamic counterpart of alertness was quasiperiodic mode as in the van der pol oscillator with sinusoidal forcing. different strange attractors were detectable in drowsiness with microsleep, light nrem sleep and in rem sleep. rapid eye movements in wakefulness and rem sleep as well as rolling eye movements in drowsiness and nrem sleep had chaotic dynamics with periodic trend and variable cd (2.9-4.5). among the significant results of this study was the demonstratio…”
Cao, T., Wang, L., Sun, Z., Engel, S. A., & He, S.. (2018). The independent and shared mechanisms of intrinsic brain dynamics: Insights from bistable perception. Frontiers in Psychology
Plain numerical DOI: 10.3389/fpsyg.2018.00589
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“In bistable perception, constant input leads to alternating perception. the dynamics of the changing perception reflects the intrinsic dynamic properties of the ‘unconscious inferential’ process in the brain. under the same condition, individuals differ in how fast they experience the perceptual alternation. in this study, testing many forms of bistable perception in a large number of observers, we investigated the key question of whether there is a general and common mechanism or multiple and independent mechanisms that control the dynamics of the inferential brain. bistable phenomena tested include binocular rivalry, vase-face, necker cube, moving plaid, motion induced blindness, biological motion, spinning dancer, rotating cylinder, lissajous-figure, rolling wheel, and translating diamond. switching dynamics for each bistable percept was measured in 100 observers. results show that the switching rates of subsets of bistable percept are highly correlated. the clustering of dynamic properties of some bistable phenomena but not an overall general control of switching dynamics implies that the brain’s inferential processes are both shared and independent – faster in constructing 3d structure from motion does not mean faster in integrating components into an objects.”
Dalseth, N., Reed, R. S., Hennessy, M., Eisenberg, M. M., & Blank, M. B.. (2018). Does Diagnosis Make a Difference? Estimating the Impact of an HIV Medication Adherence Intervention for Persons with Serious Mental Illness. AIDS and Behavior
Plain numerical DOI: 10.1007/s10461-017-1795-5
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“In multi-stable perception, past dominance of one appearance facilitates renewed dominance of the same appearance, especially after long (>10 s) blank intervals [pastukhov et al, 2008 j vis 8(13):7, 1-14]. after similarly long blank intervals, a low-contrast prime facilitates the subsequent detection of the same stimulus [tanaka and sagi, 1998 pnas 92(21) 12729-12733]. might these effects of high-contrast (hc) primes on multi-stable appearance and of low-contrast (lc) primes on threshold perception be related? we manipulated the ambiguity of hc primes by varying the strength of the perceptually suppressed parts. the priming effect of hc stimuli (binocular rivalry, necker cube, kinetic-depth effect) depended on their ambiguity and disappeared for unambiguous hc primes. intriguingly, low contrast restored the effect of an unambiguous prime on multi-stable appearance: indeed, priming strength was inversely related to contrast. in a separate series of experiments, we found that ambiguous hc primes facilitated threshold perception, just as unambiguous lc primes did. in summary, both ambiguous hc and unambiguous lc stimuli induce a novel type of perceptual memory (which is neither iconic nor visual short-term memory) and which in turn facilitates both multistable dominance and threshold perception. surprisingly, this type of memory seems to play a pervasive role in visual perception.”
Snell, T. L., McLean, L. A., McAsey, F., Zhang, M., & Maggs, D.. (2018). Nature Streaming: Contrasting the Effectiveness of Perceived Live and Recorded Videos of Nature for Restoration. Environment and Behavior
Plain numerical DOI: 10.1177/0013916518787318
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“This study investigated whether a video of a natural landscape would be more effective for restoration, including attention restoration and recovery from stress, when perceived as live rather than recorded. in total, 60 participants undertook attention-expending and stress inducing tasks, before being randomly assigned to one of three conditions (perceived live video, recorded video, and control). attention recovery was assessed using digit span backwards (dsb) and the necker cube pattern control (ncpc) pre- and post-condition, while stress was measured via skin conductivity, heart rate, and heart rate variability. we found that only participants in the live group significantly improved on the ncpc, whereas stress recovery was similar for both perceived live and recorded groups. our findings suggest that a perceived live stream of nature may allow for greater cognitive inhibition, an important aspect of learning, whereas both perceived live and recorded videos effectively reduced sympathetic stress responses.”
Brändas, E. J.. (2018). Molecular Foundation of Evolution. Advances in Quantum Chemistry
Plain numerical DOI: 10.1016/bs.aiq.2018.06.008
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“Darwinian evolution is reconsidered from a microscopic perspective commensurate with modern advanced molecular readings of our physical world and its mathematical structure. fundamental biological processes in physical complex enough systems, ces, are defined and analyzed. the material description contrives molecular events at precise temperatures and specific timescales reflecting a fundamental spatiotemporal character of a conceptual class of correlated dissipative structures, cds. the latter is subject to a higher-order statistical ensemble, the correlated dissipative ensemble, cde, reminding of dawkins’ notion of an evolution of evolvability. the ontological question is reviewed incorporating the material and the immaterial parts of nature. the exposition integrates well-defined teleonomic processes, objectively governed by an evolved program, leading up to a self-referential hypothesis for molecular communication, communication simpliciter. the principal unit of selection is intrinsic to the molecular genetic level and proceeds toward an extended phenotype that implicates perception and cognition. it is explicitly proven that active and mirror neurons provide communication protocols for cellular recognition and networking. the paradox of upside-down vision is explained together with a basic and straightforward analysis of the necker cube and the spinning dancer illusions.”
Benedek, G., & Caglioti, G.. (2019). Graphics and quantum mechanics—The necker cube as a quantum-like two-level system. In Advances in Intelligent Systems and Computing
Plain numerical DOI: 10.1007/978-3-319-95588-9_12
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Albu, M., & Szondy, M.. (2029). Relation of hot and cold executive functions with mindfulness. In ESCOP 2013: 18th Meeting of the European Society for Cognitive Psychology, Budapest, Hungary, August 29-September 1, 2013 [Abstracts]
Plain numerical DOI: 10.1037/e636952013-275
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“Aim: mindfulness involves nonjudgmental attention to present-moment experience. this study investigated the link between self-reported mindfulness and hot- (emotional and social skills) and cold (cognitive) executive control processes. method: the study addresses the relationship between a dispositional measure of mindfulness (ffmq, baer et al., 2006) and measures of attention, cognitive inhibition (stroop interference task), working memory tasks, cognitive flexibility (necker cube illusion). beside these tests of cognitive executive functions neuropsychological measures of emotions were used, as well. results: overall the results suggest that working memory, stroop-interference and cognitive flexibility are positively related to levels of mindfulness. correlations between self-reported mindfulness and all cognitive executive measurements were of moderate to high strength. furthermore, necker cube illusion measuring cognitive flexibility could be used as an objective tool for measuring mindfulness abilities. on the other hand emotional and social skills measurements exhibited a negative correlation with self-reported mindfulness (especially with nonjudging factor). conclusions: this pattern of results suggests that mindfulness is intimately linked to improvement of executive functions and cognitive flexibility. emotional functions tend to show an inverse pattern, explained by the fact that mindfulness-based interventions are focusing on reduction of emotionality. the relevance of these findings for mental balance and well-being are discussed. (psycextra database record (c) 2014 apa, all rights reserved)”
