Chapter 12 - The Asynchrony of Visual Perception

Abstract

The term perception time refers to the time between the appearance of a stimulus in the field of view and the moment a human individual subjectively experiences this stimulus. This chapter addresses the question whether different attributes of a stimulus are perceived at exactly the same time after the appearance of the stimulus, or at different times. Several studies have compared reaction times to motion and color stimuli with varying results, depending upon the method. There is no way, however, in which information from these studies can be used to address the problem of differences in perception time, not to mention measuring perception time per se. The obvious reason is that nobody knows what elapses between sensory perception and motor reaction. This might differ between reactions to different visual attributes, so one cannot equate the perception-to-reaction time interval between, say, color and motion, and thus estimate stimulation-to-perception differences based on stimulation-to-reaction data. The currently available evidence leads one to accept the notion of a perceptual asynchrony in vision. This is consistent with the theory of functional specialization in the visual brain, which it in fact consolidates.