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Ross Goutcher, Pascal Mamassian; Temporal dynamics of stereo correspondence matching. Journal of Vision 2004;4(8):600. doi: 10.1167/4.8.600.
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© ARVO (1962-2015); The Authors (2016-present)
Periodic, ‘wallpaper’ stereograms offer multiple viable solutions to the stereo correspondence problem. With prolonged viewing, observers′ perception of such stimuli can alternate between distinct correspondence solutions. Here we examine the temporal dynamics of this perceptual alternation. Participants were presented with a periodic stereogram that elicited the perception of a single frontoparallel plane, with either crossed or uncrossed disparity. This stimulus was presented for one minute and participants were asked to report the sign of the disparity at the sound of an auditory ‘beep’ presented every 2s. The presentation of this ‘beep’ was randomly jittered in time to avoid any effects of anticipation. We attempt to bias matching towards one interpretation of the stimulus by adding a small disparity pedestal to the stereogram. The addition of a disparity pedestal places either the crossed or uncrossed surface closer to fixation. Results were analysed in terms of the probability of a perceptual reversal occurring, and of a given percept surviving from one response to the next. After only a few seconds, observers′ reversal rates conformed to a stationary regime. The effects of the disparity pedestal were clearly evident during this stationary regime. The addition of a disparity pedestal increased the probability of making the correspondence solution that resulted in a surface closer to fixation. Furthermore, such a disparity pedestal increased the probability of this percept surviving between consecutive responses. These results show that perceptual alternation in correspondence matching is not chaotic and shares many characteristics with other ambiguous stimuli. Studying the temporal dynamics of perceptual alternation with ambiguous stereograms may help us to better understand the processes underlying stereo correspondence matching.
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