Abstract
How does memory retrieval contribute to eye guidance while experience is accumulating in familiar environments? Observers performed a search task in which they had to locate the person in the scene (photographs of urban environments). Critically, the delay between scene onset and initial eye movement was manipulated: one group of observers remained at central fixation for 300 ms prior to moving their eyes, while another group remained at central fixation for 1300 ms. Trials ended when the target was fixated for 750 ms. Over 8 blocks of search, some scenes were repeated and some were novel. On a final “test” block, the delay duration was either lengthened (for short-delay group) or shortened (for long-delay group). We compared how search time for familiar scenes improved over repetition.
As scenes became increasingly familiar, observers who remained at central fixation for 1300 ms showed a larger search improvement than observers who remained for 300 ms. Interestingly, this benefit manifested in the second half of the experiment. Eye movement measures showed no significant difference between the groups for blocks 1–4. For blocks 5–8, however, lower search times, fewer fixations, and shorter cumulative saccade distance were exhibited by the group with longer time for memory retrieval before search initiation. Importantly, the final “test” block showed no difference between the groups, indicating that short-delay observers had the capacity to manifest very efficient search if given sufficient time for memory retrieval. One additional finding of our study showed an impact of memory on the latency of initiating the first saccade in the scene. Observers in both groups showed a small but progressive decline in initial saccade latency (54 ms over blocks 1–8). These results suggest that achieving memory retrieval prior to initiating search, particularly early in learning, may enhance the efficacy of eye guidance in familiar environments.
NSF Graduate Research Student Fellowship