Minimal use of Working Memory in a Scene Comparison Task

摘要

Eye movement behavior in hand-eye tasks suggests a preference for a 'just in time' processing strategy that minimizes the use of working memory. In the present study, a scene comparison task was introduced to determine whether the preference holds when the task is primarily visual and when more complex naturalistic scenes are used as stimuli. Participants made same or different judgments in response to simultaneously presented pairs of scenes that were identical or differed by one object. In Experiment 1, differences were created by deleting an object, replacing it with an item from the same basic-level category (different-token) or replacing it with an item from a different basic-level category (different-type). The number of fixations per scene glance and the number of fixations intervening between glances to corresponding objects suggest that frequently one object at a time is encoded and maintained in visual working memory. In Experiment 2, different-types and different tokens were administered in separate blocks in order to determine whether the one-to-one viewing strategy was driven by the need to encode the visual details of the objects. There were no differences between conditions, suggesting that the minimal memory preference generalizes to the case when only the identity of the object is needed. An object array version of the task was introduced in Experiment 3 to further test the persistence of the minimal memory preference by requiring the items to be encoded at the level of the identity of the objects. Overall, the results suggest a strong general bias toward minimal use of visual working memory in complex visual tasks.