Distinct roles of eye movements during memory encoding and retrieval.

A long line of research has shown that vision and memory are closely linked, such that particular eye movement behaviour aids memory performance. In two experiments, we ask whether the positive influence of eye movements on memory is primarily a result of overt visual exploration during the encoding or the recognition phase. Experiment 1 allowed participants to free-view images of scenes, followed by a new-old recognition memory task. Exploratory analyses found that eye movements during study were predictive of subsequent memory performance. Importantly, intrinsic image memorability does not explain this finding. Eye movements during test were only predictive of memory within the first 600 ms of the trial. To examine whether this relationship between eye movements and memory is causal, Experiment 2 manipulated participants' ability to make eye movements during either study or test in a new-old recognition task. Participants were either encouraged to freely explore the scene in both the study and test phases, or had to refrain from making eye movements in either the test phase, the study phase, or both. We found that hit rate was significantly higher when participants moved their eyes during the study phase, regardless of what they did in the test phase. False alarm rate, on the other hand, was affected only by eye movements during the test phase: it decreased when participants were encouraged to explore the scene. Taken together, these results reveal a dissociation of the role of eye movements during the encoding and recognition of scenes. Eye movements during study are instrumental in forming memories, and eye movements during recognition support the judgment of memory veracity.