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Jonathan Kominsky, Brian Scholl; The window of 'postdiction' in visual perception is flexible: Evidence from causal perception. Journal of Vision 2012;12(9):309. doi: 10.1167/12.9.309.
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© ARVO (1962-2015); The Authors (2016-present)
One of the most counterintuitive effects in perception is postdiction — the ability of the visual system to integrate information from shortly after an event occurs into the perception of that very event. Postdictive effects have been found in many contexts, but their underlying nature remains somewhat mysterious. Here we report several studies causal perception that explore whether the temporal extent of the postdiction 'window' is fixed, or whether it can flexibly adapt to different contexts. Previous work has explored a display in which one disc (A) moves to fully overlap a second disc (B), at which point A stops and B starts moving. This 'full-overlap' display will often be seen in terms of non-causal 'passing', wherein A is seen to pass over a stationary B (even when their colors differ). However, when a third 'context' object (C) begins moving in the same direction as B at roughly the same time, the full-overlap event will often be perceived as causal 'launching', wherein A collides with B, causing it's motion. These percepts can be influenced postdictively, when C begins moving slightly after the A/B overlap. By varying the objects' speeds, we were able to determine whether the duration of the postdiction window is a constant, or whether it varies as a function of an event's pace. The results clearly demonstrated that the postdiction window is flexible, and in a surprising way. The existence of a postdictive effect was a function not just of the temporal offset (between when B and C started moving) but also of a spatial offset — how far B had moved before C started moving, largely independent of the timing. This suggests that the visual system is adapting to the speed of the stimuli and adjusting the extent of the postdiction 'window' accordingly.
Meeting abstract presented at VSS 2012
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