Abstract
Alvarez and Scholl (in press) found that when several moving objects are tracked, attention is concentrated at the center of each object. Other literature has shown that the visual system attentionally prioritizes spatial locations based on the probabilities of stimuli appearing at each location (e.g., Geng & Behrmann, in press). Here we hypothesize that when tracking several moving objects, attention focuses on the most strategically advantageous locations, which may be the centers of objects or other locations. In a multiple object tracking task, observers tracked several long moving lines among identical distractors. Small circular probes appeared briefly on target lines, and observers' performance at detecting probes was used to measure the distribution of attention. The probability of a probe occurring at different locations was manipulated. When probes were most likely to appear on the centers of lines, probe detection was much more accurate at centers than near the ends of lines. However, when probes were most likely to appear near one of the endpoints of each line, detection was more accurate near those endpoints than at the centers, although this difference in detection rates was smaller. This suggests that when tracking several moving objects, there is an attentional bias toward centers of objects, however the attentional distribution is also affected by strategic factors such as spatial probabilities. Regarding findings that spatial locations are attentionally prioritized based on their probabilities of containing stimuli, our results suggest that these attentional prioritizations can move along with a continuously moving object.
Supported by KY NSF EPSCoR Grant 11-223162