Item

Abstract

Attention determines which aspects of the incoming sensory information are processed with priority. However, attention is seldom an all-or-none process but rather distributed over multiple kinds of incoming information, and this distribution must be updated according to events in the world. Despite its ubiquity, this dynamic updating has been little studied in psychophysics, and even less is known about its neural correlates. In order to investigate attention updating, we studied serial detection of targets in different dimensions (color, shape or motion) of visual stimuli. Performance changed according to target sequence, and could be explained by this simple behavioral model: Each detected target was followed by a discrete attention shift towards the dimension in which the target occurred, leading to a short-lasting, exponentially decaying performance benefit. Continuously changing performance over time reflected the dynamic updating of attention induced by the sequence of detected targets. BOLD signal predicted by this time-course of attention changes was found exclusively in left parietal cortex, suggesting that neural activity in this area directly reflects how world events influence the distribution of attention.