The effects of target template specificity on visual search in real-world scenes: evidence from eye movements

We can locate an object more quickly in a real-world scene when a specific target template is held in visual working memory, but it is not known exactly how a target template's specificity affects real-world search. In the present study, we compared word and picture cues in real-world scene search. Using an eye-tracker, we segmented search time into three behaviorally defined epochs: search initiation time, scanning time, and verification time. Results from three experiments indicated that target template specificity affects scanning and verification time. Within the scanning epoch, target template specificity affected the number of scene regions visited and the mean fixation duration. Changes to SOA did not affect this pattern of results. Similarly, the pattern of results did not change when participants were familiarized with target images prior to testing, suggesting that an immediately preceding picture provides a more useful search template than one stored in long-term memory. The results suggest that the specificity of the target cue affects both the activation map representing potential target locations and the process that matches a fixated object to an internal representation of the target.