The discrimination of correlated and anti-correlated motion in the human visual system

Abstract

Introduction: how the brain integrates spatial and temporal information is not known. This issue is referred to as the “binding problem” of visual perception. It has been proposed that groups of neurons which correspond to the same elements of an image become synchronous in order to form a coherent neural representation; however, direct experimental evidence supporting this role for neural synchrony is highly controversial. as our perceptual capabilities are limited by the neural mechanism that supports them, an alternative approach to understanding neural synchrony is to instead characterize our ability to perceive synchrony. Thus, our aim was to demonstrate how correlated (i.e., synchronous) motion is perceived by the brain and how its discrimination can be enhanced or impaired. Methods: In this study, we used human psychophysics experiments to characterize the ability of subjects to discriminate synchrony in a moving visual stimulus. results: By varying stimulus length, motion speed, and direction we found that humans were less than optimal in their ability to discriminate correlated motion when compared to an ideal mathematical model. In addition, we found that the length of the entire stimulus was not an important factor, but the length of individual motion pulses which made up the stimulus was crucial to performance. discussion: overall these results suggest that neural synchrony is likely used by the brain, but its resolution is highly limited compared to an ideal model.