The effect of disparity on the perception of motion-defined contours

GONZALES CHAMBEAUD, J.; MARTÍN A.; BARRAZA J.F.

Psychology & Neuroscience

PUC-Rio

Lugar: Río de Janeiro; Año: 2014 vol. 7 p. 91 - 101

1983-3288

We present three experiments to explore the effect of binocular disparity on the perception of contours defined by motion in Spatiotemporal Boundary Formation (SBF). Depending on disparity, the stimulus is perceived as an object moving behind a holed surface (occluded configuration), or as a luminous transparency moving over a surface containing dots (occluding configuration).For all experiments, we used a Vernier task to assess the strength of the contour perception. In the first experiment, we measured acuity as a function of disparity for a range of speed and dot density. Results show that, despite the difference in the percepts, acuity is similar in both situations, and it replicates the dependence on speed and dot density showed in previous studies. In the second experiment, results show that the dynamics of the contour integration is identical for both, occluded and occluding configurations. Finally, we tested whether the mechanism of contour integration works independently from the interpretation of the scene. In this experiment, we inverted the disparity during the stimulus presentation, so that the stimulus switches between occluded and occluding configurations. Results show that the switch of the depth order increases the threshold to a value obtained with a shorter presentation time. This might be produced by a reset of the integration process driven by the change of the depth order. Results are discussed within a conceptual model which sets the process of contour integration in the context of the perception of objects in SBF.