Eye movement strategies during attentional tracking
Fehd, Hilda M.
Though it is a common occurrence during activities such as team sports to have to attend to multiple objects at once, we are only able to direct gaze to one location at a time. Where will gaze be directed when there are multiple locations of interest of which an observer wants to keep track? Preliminary evidence indicates that, when simultaneously tracking several moving targets amidst distractors, participants primarily looked at a central point in between the targets. This study explores the nature of this center-viewing strategy, examining what factors influence the use of the strategy as well as its effectiveness. First I determined that center-viewing does not result from avoiding costly eye movements during tracking as it persisted when targets move slow enough to reduce the cost of any eye movements made. Next, I found that center-viewing does appear to depend on the ability to distinguish targets peripherally, as it diminished when participants were pushed to their perceptual limits. Then, I determined that center-viewing does not seem to reflect the attentional weighting given to the attended locations. Further, I found that the root of center-viewing does not lie in a tendency to group the attended targets into a single object, as it was not found to vary when the ease of target segregation was manipulated. Finally, I established that center-viewing is more beneficial strategy for tracking than target-viewing by directly comparing participants’ performance when they actively controlled their gaze to engage in each strategy. Results from these experiments show that directing gaze to the center of multiple items that are competing for attention at the same time is an effective strategy for keeping track of them all. However, this strategy does not seem to be a result of eye movement avoidance, attentional distribution, or grouping the targets together. Center-viewing may be the result of a gaze optimizing strategy where maintaining fixation at the center of an array of attended information is only one of many factors involved in the optimization process.