Visual memory for pictorial stimuli in a serial choice reaction-time task.

Three experiments investigated the nature of the single-item visual recency effect in the serial choice reaction-time task (Rabbitt & Vyas, 1979; Walker & Marshall, 1982). The first experiment demonstrated that, like single letters varying in case, pictorial stimuli yield visual priming that is limited to consecutive stimuli and is unaffected by the presentation of an irrelevant stimulus in the response-stimulus interval. The second experiment confirmed that repeating a picture produces facilitation over and above repeating the object that it portrays. In addition, it was observed that name priming, but not visual or object priming, decreases with practice. This indicated that visual priming and object priming occur during identification. Finally, in Expt 3, an irrelevant picture was presented unpredictably in the response-stimulus interval. Previous results had suggested that this manipulation would provide evidence for distinct visual and object codes. Although the results were inconclusive, they do indicate that time intervals and presence of intervening information per se do not explain the loss of visual and object priming effects. It was suggested that the unpredictable irrelevant stimulus may have been disrupting a process whereby memory and perception interact directly at the level of a visual code.