Spatiotemporal feature attribution for the perception of visual size

This study examined the role of spatiotemporal feature attribution in the perception of the visual size of objects. A small or a large leading disk, a test disk of variable size, and a probe disk of a fixed size were sequentially presented at the same position for durations of 16.7 ms with interstimulus intervals of 117 ms. Observers compared the visual size of the test with the probe disk. The size of the test disk was underestimated and overestimated when the test followed small and large leading disks, respectively (Experiment 1). These modulations of visual size occurred even when disks were sequentially presented so as to invoke apparent motion (Experiment 2). Furthermore, when two streams of apparent motion consisting of the three types of disk were diagonally overlapped, modulation of visual size occurred in accordance with the size of the attended leading disk (Experiment 3). Retinotopic and non-retinotopic feature attribution and the related attentional mechanisms are discussed.