High-capacity spatial contextual memory.

Humans show implicit memory for complex spatial layouts, which aids in subsequent processing of these layouts. Research efforts in the past 5 years have focused primarily on a single session of training involving a dozen repeated displays. Yet every day, people encounter many more visual layouts than were presented in such experiments. In this study, we trained subjects to learn 60 repeated displays, randomly intermixed within 1,800 nonrepeated displays, spread over 5 consecutive days. On each day, the subjects conducted visual search on 360 new displays and a new set of 12 repeated displays, each repeated 30 times. Contextual memory was observed daily. One week after the fifth session, the subjects still searched faster on the repeated displays learned previously. We conclude that the visual system has a high capacity for learning and retaining repeated spatial context, an ability that may compensate for our severe limitations in visual attention and working memory.