Examining the effects of passive and active strategies on behavior during hybrid visual memory search: evidence from eye tracking

Hybrid search requires observers to search both through a visual display and through the contents of memory in order to find designated target items. Because professional hybrid searchers such as airport baggage screeners are required to look for many items simultaneously, it is important to explore any potential strategies that may beneficially impact performance during these societally important tasks. The aim of the current study was to investigate the role that cognitive strategies play in facilitating hybrid search. We hypothesized that observers in a hybrid search task would naturally adopt a strategy in which they remained somewhat passive, allowing targets to “pop out.” Alternatively, we considered the possibility that observers could adopt a strategy in which they more actively directed their attention around the visual display. In experiment 1, we compared behavioral responses during uninstructed, passive, and active hybrid search. We found that uninstructed search tended to be more active in nature, but that adopting a passive strategy led to above average performance as indicated by a combined measure of speed and accuracy called a balanced integration score (BIS). We replicated these findings in experiment 2. Additionally, we found that oculomotor behavior in passive hybrid search was characterized by longer saccades, improved attentional guidance, and an improved ability to identify items as targets or distractors (relative to active hybrid search). These results have implications for understanding hybrid visual search and the effect that strategy use has on performance and oculomotor behavior during this common, and at times societally important, task.