Ambiguous plaids: Switching between coherence and transparency

Grünau, Michael von; Dubé, Stéphane

doi:10.1163/156856893x00360

Cited by 23 publications

(8 citation statements)

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“…The three panels are computed for three different normal speed ratios. (Hupé & Rubin, 2003;von Grünau & Dubé, 1993). Given that our experiments were performed with short duration stimulus exposures (1.5 s), it is unlikely that our subjects would have experienced a transition from one state to the other.…”

Section: Discussionmentioning

confidence: 99%

Optimal inference explains the perceptual coherence of visual motion stimuli

2011

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The local spatiotemporal pattern of light on the retina is often consistent with a single translational velocity which may also be interpreted as a superposition of spatial patterns translating with different velocities. Human perception reflects such interpretations, as can be demonstrated using stimuli constructed from a superposition of two drifting gratings. Depending on a variety of parameters, these stimuli may be perceived as a coherently moving plaid pattern or as two transparent gratings moving in different directions. Here, we propose a quantitative model that explains how and why such interpretations are selected. An observer's percept corresponds to the most probable interpretation of noisy measurements of local image motion, based on separate prior beliefs about the speed and singularity of visual motion. This model accounts for human perceptual interpretations across a broad range of angles and speeds. With optimized parameters, its components are consistent with previous results in motion perception.

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Section: Discussionmentioning

confidence: 99%

Optimal inference explains the perceptual coherence of visual motion stimuli

2011

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“…A similar phenomenon has been reported in the visual modality. When viewing ambiguous dynamic plaids constructed from two drifting gratings at intermediate speed and angle, observers have reported first experiencing coherent motion of a unified plaid pattern, even when, in the long term, their perception is biased toward transparent motion of the individual gratings in each of their component directions (Von Grünau and Dubé, 1993 ; Hupé and Rubin, 2003 ; Rubin and Hupé, 2004 ; Hupé and Pressnitzer, 2012 ). The probability of observers reporting a split perceptual organization over time can be quantified as a buildup function.…”

Section: Introductionmentioning

confidence: 99%

An alternating renewal process describes the buildup of perceptual segregation

Steele

Tranchina

Rinzel

2015

Front. Comput. Neurosci.

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For some ambiguous scenes perceptual conflict arises between integration and segregation. Initially, all stimulus features seem integrated. Then abruptly, perhaps after a few seconds, a segregated percept emerges. For example, segregation of acoustic features into streams may require several seconds. In behavioral experiments, when a subject's reports of stream segregation are averaged over repeated trials, one obtains a buildup function, a smooth time course for segregation probability. The buildup function has been said to reflect an underlying mechanism of evidence accumulation or adaptation. During long duration stimuli perception may alternate between integration and segregation. We present a statistical model based on an alternating renewal process (ARP) that generates buildup functions without an accumulative process. In our model, perception alternates during a trial between different groupings, as in perceptual bistability, with random and independent dominance durations sampled from different percept-specific probability distributions. Using this theory, we describe the short-term dynamics of buildup observed on short trials in terms of the long-term statistics of percept durations for the two alternating perceptual organizations. Our statistical-dynamics model describes well the buildup functions and alternations in simulations of pseudo-mechanistic neuronal network models with percept-selective populations competing through mutual inhibition. Even though the competition model can show history dependence through slow adaptation, our statistical switching model, that neglects history, predicts well the buildup function. We propose that accumulation is not a necessary feature to produce buildup. Generally, if alternations between two states exhibit independent durations with stationary statistics then the associated buildup function can be described by the statistical dynamics of an ARP.

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“…In previous studies (von Grünau & Dubé, 1993), we have shown that unambiguous adaptation to either component or pattern motion can alter the proportion of coherence in a bistable plaid stimulus. Thus, adaptation to a component stimulus resulted in a reduction of time for the percept of component motion (sliding motion).…”

Section: General Methodsmentioning

confidence: 71%

“…In previous experiments of the same type (von Grünau & Dubé, 1993; von Grünau et al, 1993), analyses of the lengths of the individual episodes showed that adaptation to pattern motion affected only the length of time for which coherence was perceived, while adaptation to component motion affected only the lengths of component episodes. In both cases, adaptation led to a reduction of the lengths of the respective episodes, while the other episodes were not affected.…”

Section: Discussionmentioning

confidence: 91%

The effects of motion adaptation and disparity in motion integration.

Kwas

Grünau²,

Dubé³

1995

Canadian Journal of Experimental Psychology / Revue canadienne

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Two experiments examined the effects of pattern vs component adaptation on motion integration in stimuli with or without disparity. Observers adapted to either downward pattern motion, downward component motion, or a grey screen, and were then tested with plaids containing either crossed, uncrossed or zero binocular disparity, moving downward. In a second experiment, the same test conditions were employed following adaptation to upward pattern motion. The total amount of time that coherence or transparent sliding was perceived was measured. Adaptation to component motion increased the amount of perceived coherent motion whereas adaptation to pattern motion decreased it. The second experiment revealed that adaptation to the upward-moving pattern had no effect on perceived coherence. The results demonstrate the complex nature of the interaction between depth and motion mechanisms in motion integration. Under prolonged inspection, a moving squarewave plaid 1 yields bistable percepts: Perception switches between separate gratings sliding over one another in their respective directions, and a coherent plaid moving in a third direction. The "separate" percept implies that each grating is processed by an appropriate direction-sensitive mechanism and that both are operating simultaneously. This is also referred to as the stage of component motion. The "coherent" percept implies a further stage of processing, whereby the two component gratings are integrated into a new pattern, a plaid, which moves in a composite direction, different from the two original directions. This stage has been referred to as pattern motion, and models have been developed to describe the perceived pattern direction (Adelson & Movshon, 1982; 1 Plaid stimuli are constructed by superimposing two grating stimuli of different orientations that may also differ in terms of their spatial frequency and contrast and other parameters. Each individual grating moves in a direction perpendicular to its orientation. The areas where the grating lines cross each other are called intersections and have a luminance that may differ from those of the peaks and troughs of the gratings, thus giving the plaid-like appearance of the compound stimulus.

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Ambiguous plaids: Switching between coherence and transparency

Cited by 23 publications

References 0 publications

Optimal inference explains the perceptual coherence of visual motion stimuli

Optimal inference explains the perceptual coherence of visual motion stimuli

An alternating renewal process describes the buildup of perceptual segregation

The effects of motion adaptation and disparity in motion integration.

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