Stereoscopic occlusion and the aperture problem for motion: a new solution.

Area of Science:

• * Visual perception
• * Computational neuroscience
• * Psychophysics

Background:

• * Perceived motion of untextured contours depends on classifying contour terminators as intrinsic or extrinsic.
• * Stereopsis, using binocular disparity, influences this classification, with prior work suggesting relative depth is key.
• * The barberpole illusion demonstrates how contour terminators influence motion perception.

Purpose of the Study:

• * To investigate whether the visual system uses unpaired contour terminators to classify stereoscopic contour terminators as extrinsic.
• * To determine if local, unpaired contour terminators, rather than relative depth or disparity, drive this classification.
• * To explore the role of contour terminator pairing in the barberpole illusion and motion perception.

Main Methods:

• * Presented untextured contours translating within rectangular and square apertures.
• * Manipulated interocular pairing of contour terminators along aperture edges.
• * Assessed perceived motion direction under varying stereoscopic depth conditions.

Main Results:

• * The barberpole illusion persisted with stereoscopic depth differences when contour terminators were interocularly paired.
• * The illusion was abolished when contour terminators along the aperture's longer axis were interocularly unpaired.
• * A square aperture showed a motion shift towards binocularly paired terminators.

Conclusions:

• * The visual system classifies stereoscopic contour terminators as extrinsic based on the presence of local, unpaired terminators.
• * This classification relies on local cues of unpaired terminators, not solely on relative depth or disparity.
• * Findings challenge previous notions and highlight the importance of local contour features in motion perception.