Abstract
When two stationary objects at different locations are presented alternatively in succession, they can be perceived either as two stationary flickering objects, or as two objects switching back and forth between the two locations (apparent motion). Previous research suggested that attentive tracking is linked to the perception of apparent motion (Cavanagh, 1992; Verstraten, Cavanagh, & Labianca, 2000; Verstraten and Ashida, 2005). According to a strong version of this account, the correspondence problem of what went where may be determined by the position of spatial selection over time. We tested this possibility by tracking the position of spatial selection using an electrophysiological correlate (Contralateral Delay Activity). Participants were presented with an ambiguous apparent motion display (6 frames, 1.5 Hz) that could be perceived as either two objects (an “x” and a “+”) rotating or two objects switching from one location to the other. We found that when switching motion is perceived, attention was locked to one object and shifted back and forth as the selected object appeared alternatively at the two locations. The results suggest an important role of the distribution of selective attention in organizing perceptual structure over space and time.