Fig. 1.

A, Schematic diagram of the DPA task. After fixating for 2 sec, a sample object was presented at the center of gaze for 500 msec. After a subsequent 1000 msec delay, a test object was presented, which could be either a target or nontarget. The sequence of events was identical for the DMS task.B, Sample–target associations for both tasks. For each task, the test stimulus could either be a target (match) or nontarget (nonmatch). Stimuli for both tasks were chosen such that two of the three were similar to each other. Similarity is depicted as vertical proximity, such that S1 and S2, and C2 and C3 were similar and each were different from S3 and C1, respectively.