Abstract
Previously we established that, when tracking multiple objects, people tend to look at the center of the array of targets rather than saccade from target to target. The present goal was to determine whether participants attend to the location of their eye gaze during multiple object tracking. While it is possible to dissociate attention from fixation, people may attend to where they fixate as much as to peripheral targets. In the first experiment observers tracked 4 of 10 randomly moving dots. In addition to tracking, participants were asked to detect the presence of a brief flash that could occur either on a dot or the background. Eye movements were recorded using an ASL 120 Hz video-based eye tracker. Results replicated previous work by showing that gaze was closer to the targets' centroid - the center of the shape formed by the target dots for significantly more of the time (40%) than to any of the target dots (10%). Flash detection was better for flashes presented at the centroid (99%) and on targets (86%) than for those presented on distractors (72%) and blank space (76%). Equating for eccentricity, performance showed a similar, but not significant, trend. This result suggests that the center of the target array may be attended in addition to the targets. A second experiment determined whether the center was inhibited when a distractor item was presented at its location. No flashes were presented. On some trials, a target or distractor dot was shown at the centroid. Participants continued to look at the centroid when there was a distractor item there (53%), even more so than when nothing was presented there (34%). Together, the results of these two experiments suggest that people pay attention to the center of the target array when tracking multiple objects.
This work was supported by the Vanderbilt Vision Research Center and NIH EY014984.