Repetition priming reveals sustained facilitation and transient inhibitionin reaction time

Reaction time (RT) in a detection or a location discrimination task increas es when a target is repeatedly presented at the same location (inhibition), whereas RT decreases in feature (color or orientation) discrimination task s (facilitation; Y. Tanaka & S. Shimojo, 1996a). Here, the time course of i nhibition and facilitation was examined, using a repetition priming paradig m. Results indicate that inhibition occurred only in the immediately succes sive trial, whereas facilitation accumulated over several trials with locat ion repetition. Moreover, inhibition and facilitation occurred in a task-re levant manner: Detection-location discrimination tasks produced transient R T increase, whereas feature discrimination tasks produced cumulative RT dec rease. These results suggest a functional dissociation between spatial orie nting and feature analysis, as well as top-down modulations by tasks leadin g to different types of visual memory.