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Temporal dynamics of auditory and visual bistability reveal common principles of perceptual organization
- Curr. Biol
, 2006
"... When dealing with natural scenes, sensory systems have to process an often messy and ambiguous flow of information. A stable perceptual organization nevertheless has to be achieved in order to guide behavior. The neural mechanisms involved can be highlighted by intrinsically ambiguous situations. In ..."
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Cited by 36 (2 self)
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When dealing with natural scenes, sensory systems have to process an often messy and ambiguous flow of information. A stable perceptual organization nevertheless has to be achieved in order to guide behavior. The neural mechanisms involved can be highlighted by intrinsically ambiguous situations. In such cases, bistable perception occurs: distinct interpretations of the unchanging stimulus alternate spontaneously in the mind of the observer [1]. Bistable stimuli have been used extensively for more than two centuries to study visual perception [2]. Here we demonstrate that bistable perception also occurs in the auditory modality. We compared the temporal dynamics of percept alternations observed during auditory streaming [3, 4] with those observed for visual plaids [5, 6] and the susceptibilities of both modalities to volitional control. Strong similarities indicate that auditory and visual alternations share common principles of perceptual bistability. The absence of correlation across modalities for subject-specific biases, however, suggests that these common principles are implemented at least partly independently across sensory modalities. We propose that visual and auditory perceptual organization could rely on distributed but functionally similar neural competition mechanisms aimed at resolving sensory ambiguities. Results and Discussion The study of bistable perception has generated a sustained interest in visual neuroscience, as it decouples the conscious perception of the observer from the characteristics of the physical stimulation: the same stimulus evokes different percepts. This provides a powerful method to probe the neural bases of perception, because changes in neural responses that correlate with *Correspondence:
Percept-choice sequences driven by interrupted ambiguous stimuli: a low-level neural model.
- J Vis
, 2007
"... Existing neural explanations of spontaneous percept switching under steady viewing of an ambiguous stimulus do not fit the fact that stimulus interruptions cause the same percept to reappear across many ON/OFF cycles. We present a simple neural model that explains the observed behavior and predicts ..."
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Cited by 28 (2 self)
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Existing neural explanations of spontaneous percept switching under steady viewing of an ambiguous stimulus do not fit the fact that stimulus interruptions cause the same percept to reappear across many ON/OFF cycles. We present a simple neural model that explains the observed behavior and predicts several more complicated percept sequences, without invoking any "high-level" decision making or memory. Percept choice at stimulus onset, which differs fundamentally from standard percept switching, depends crucially on a hitherto neglected interaction between local "shunting" adaptation and a near-threshold neural baseline. Stimulus ON/OFF timing then controls the generation of repeating, alternating, or more complex choice sequences. Our model also explains "priming" versus "habituation" effects on percept choice, reinterprets recent neurophysiological data, and predicts the emergence of hysteresis at the level of percept sequences, with occasional
Temporal dynamics in Bistable Perception
- Journal of Vision. No
, 2005
"... Bistable perception is fundamentally a dynamic process: Our perceptual experience continuously alternates when an ambiguous or rivalrous stimulus is observed. Here we present a method to analyze instantaneous measures of dominance and transition between percepts. The analysis extracts three time-var ..."
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Cited by 23 (2 self)
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Bistable perception is fundamentally a dynamic process: Our perceptual experience continuously alternates when an ambiguous or rivalrous stimulus is observed. Here we present a method to analyze instantaneous measures of dominance and transition between percepts. The analysis extracts three time-varying probabilities. First, the transient preference represents the probability of perceiving one interpretation at one instant. Second, the reversal probability is the probability that the current percept will change at the next evaluation. Finally, the survival probabilities are the probability that at one instant the current percept will not switch to the alternative interpretation. We derive the relationships between these probabilities and offer a test of independence between consecutive percepts. We also introduce a simple technique to sample the observer’s perception at regular intervals. The analyzing method is illustrated with the example of binocular rivalry. We demonstrate Levelt’s second proposition with the survival probability measure and show that the consecutive rivalrous percepts are not independent. Keywords: bistability, perceptual dynamics, ambiguous perception, binocular rivalry, Levelt’s second proposition
G (2008) A neural basis for percept stabilization in binocular rivalry
- J Cogn Neurosci
"... & When the same visual input has conflicting interpretations, conscious perception can alternate spontaneously between each competing percept. Surprisingly, such bistable perception can be stabilized by intermittent stimulus removal, suggesting the existence of perceptual ‘‘memory’ ’ across inte ..."
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Cited by 18 (0 self)
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& When the same visual input has conflicting interpretations, conscious perception can alternate spontaneously between each competing percept. Surprisingly, such bistable perception can be stabilized by intermittent stimulus removal, suggesting the existence of perceptual ‘‘memory’ ’ across interruptions in stimulation. The neural basis of such a process remains un-known. Here, we studied binocular rivalry, one type of bistable perception, in two linked experiments in human participants. First, we showed, in a behavioral experiment using binocular rivalry between face and grating stimuli, that the stabilizing effect of stimulus removal was specific to perceptual alterna-tions evoked by rivalry, and did not occur following physical alternations in the absence of rivalry. We then used functional magnetic resonance imaging to measure brain activity in a var-iable delay period of stimulus removal. Activity in the fusiform face area during the delay period following removal of rivalrous stimuli was greater following face than grating perception, whereas such a difference was absent during removal of non-rivalrous stimuli. Moreover, activity in areas of fronto-parietal regions during the delay period correlated with the degree to which individual participants tended to experience percept stabilization. Our findings suggest that percept-related activity in specialized extrastriate visual areas help to stabilize per-ception during perceptual conflict, and that high-level mech-anisms may determine the influence of such signals on conscious perception. &
Abstract The continuous Wagon Wheel Illusion depends on, but is not identical to neuronal adaptation
, 2007
"... The occurrence of perceived reversed motion while observers view a continuous, periodically moving stimulus (a bistable phenomenon coined the ‘‘continuous Wagon Wheel Illusion’ ’ or ‘‘c-WWI’’) has been taken as evidence that some aspects of motion perception rely on discrete sampling of visual infor ..."
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Cited by 6 (2 self)
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The occurrence of perceived reversed motion while observers view a continuous, periodically moving stimulus (a bistable phenomenon coined the ‘‘continuous Wagon Wheel Illusion’ ’ or ‘‘c-WWI’’) has been taken as evidence that some aspects of motion perception rely on discrete sampling of visual information. Alternative accounts rely on the possibility of a motion aftereffect that may become visible even while the adapting stimulus is present. Here I show that motion adaptation might be necessary, but is not sufficient to explain the illusion. When local adaptation is prevented by slowly drifting the moving wheel across the retina, the c-WWI illusion tends to decrease, as do other bistable percepts (e.g. binocular rivalry). However, the strength of the c-WWI and that of adaptation (as measured by either the static or flicker motion aftereffects) are not directly related: although the c-WWI decreases with increasing eccentricity, the aftereffects actually intensify concurrently. A similar dissociation can be induced by manipulating stimulus contrast. This indicates that the c-WWI may be enabled by, but is not equivalent to, local motion adaptation – and that other factors such as discrete sampling may be involved in its generation.
Bi-stable depth ordering of superimposed moving gratings
"... Ambiguous stimuli with two distinct interpretations give rise to perceptual alternations between them. During prolonged viewing of transparently moving gratings, observers report periods of perceiving one grating in front of the other, alternating with periods of the reverse depth ordering. We measu ..."
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Cited by 4 (1 self)
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Ambiguous stimuli with two distinct interpretations give rise to perceptual alternations between them. During prolonged viewing of transparently moving gratings, observers report periods of perceiving one grating in front of the other, alternating with periods of the reverse depth ordering. We measured the percepts ’ dominance times to study the effect of depth cues (wavelength, duty cycle, and speed) on the perceived depth ordering. The grating with shorter wavelength, lower duty cycle, or higher speed was perceived as being behind the other for a fraction of time larger than one half. The fraction of time spent perceiving each grating as behind changed gradually as a function of the parameters. The fraction of dominance depended on the ratio between the gratings ’ wavelengths, not on their absolute sizes. The wavelength ratio had a stronger effect on perceived depth than that of duty cycle or speed and could override stereoscopic disparity cues. Similar results were obtained with superimposed moving surfaces of random dots. The findings are interpreted in terms of their relation to statistical properties of natural surfaces and provide evidence that the fraction of dominance of each percept represents the likelihood that it corresponds to the true interpretation of the underlying scene.
Untangling perceptual memory: hysteresis and adaptation map into separate cortical networks. Cereb. Cortex 24, 1152–1164. doi: 10.1093/ cercor/bhs396
- Perception
, 2014
"... Perception is an active inferential process in which prior knowledge is combined with sensory input, the result of which determines the contents of awareness. Accordingly, previous experience is known to help the brain “decide ” what to perceive. However, a critical aspect that has not been addresse ..."
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Cited by 3 (0 self)
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Perception is an active inferential process in which prior knowledge is combined with sensory input, the result of which determines the contents of awareness. Accordingly, previous experience is known to help the brain “decide ” what to perceive. However, a critical aspect that has not been addressed is that previous experience can exert 2 opposing effects on perception: An attractive effect, sensi-tizing the brain to perceive the same again (hysteresis), or a repul-sive effect, making it more likely to perceive something else (adaptation). We used functional magnetic resonance imaging and modeling to elucidate how the brain entertains these 2 opposing processes, and what determines the direction of such experience-dependent perceptual effects. We found that although affecting our perception concurrently, hysteresis and adaptation map into distinct cortical networks: a widespread network of higher-order visual and fronto-parietal areas was involved in perceptual stabilization, while
Noise and adaptation in multistable perception: noise drives when to switch, adaptation determines percept choice
, 2014
"... We study the dynamics of perceptual switching in ambiguous visual scenes that admit more than two interpretations/percepts to gain insight into the dynamics of perceptual multistability and its underlying neural mechanisms. We focus on visual plaids that are tristable and we present both experimenta ..."
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Cited by 1 (1 self)
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We study the dynamics of perceptual switching in ambiguous visual scenes that admit more than two interpretations/percepts to gain insight into the dynamics of perceptual multistability and its underlying neural mechanisms. We focus on visual plaids that are tristable and we present both experimental and computational results. We develop a firing-rate model based on mutual inhibition and adaptation that involves stochastic dynamics of multiple-attractor systems. The model can account for the dynamic properties (transition probabilities, distributions of percept durations, etc.) observed in the experiments. Noise and adaptation have both been shown to play roles in the dynamics of bistable perception. Here, tristable perception allows us to specify the roles of noise and adaptation in our model. Noise is critical in considering the time of a switch. On the other hand, adaptation mechanisms are critical in considering perceptual choice (in tristable perception, each time a percept ends, there is a possible choice between two new percepts).
The role of lateral inhibition in binocular motion rivalry
"... It is generally believed that percept alternations in binocular rivalry result from the interplay between mutual inhibition and slow adaptation of the competing percepts. This view is supported by growing evidence that dynamic changes in adaptation indeed support percept alternations in binocular r ..."
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It is generally believed that percept alternations in binocular rivalry result from the interplay between mutual inhibition and slow adaptation of the competing percepts. This view is supported by growing evidence that dynamic changes in adaptation indeed support percept alternations in binocular rivalry. Empirical evidence for the involvement of mutual inhibition, however, is still scarce. To fill this gap, we presented human subjects with dichoptic random-dot motion stimuli and manipulated the angle between the monocular directions of motion from pure opponent horizontal motion to pure vertical motion in the same direction. We hypothesized that this decrease in motiondirection disparity increases the cross-inhibition gain due to lateral inhibition between neurons in the brain that are coarsely tuned to adjacent directions of visual motion, which predicts the largest changes in dominance at the smallest instead of the largest motion-direction disparities. We found that decreasing the angle between the two monocular directions of motion indeed systematically increased the predominance and mean dominance durations of the motion pattern presented to the ocular dominant eye (as identified by the hole-incard test). Moreover, this effect was stronger if the contrast of the stimuli was lowered. Simulations showed that these features are indeed hallmark of weighted lateral inhibition between populations of directionally tuned motion-sensitive neurons. Our findings thus suggest dominance and suppression in binocular rivalry arises naturally from this fundamental principle in sensory processing. Interestingly, if the two monocular directions of motion differed ,608, the percept alternations also included transitions to in-between (vertical) motion percepts. We speculate that this behavior might result from positive feedback arising from adapting disinhibitory circuits in the network.
