INHIBITION OF RETURN IN LOCATION-BASED AND IDENTITY-BASED CHOICE DECISION TASKS

Three experiments were conducted to determine whether inhibition of re turn can be best characterized as an attentional or a motor phenomenon . In the first experiment, subjects made choice key-press responses to the location of a target (left or right) or the identity of the targe t (X or +) by pressing a left or right response key. In the second exp eriment, the display was rotated 90 degrees so that there was no direc t spatial mapping between the vertically aligned stimulus display and the horizontally aligned response keys. In both experiments, inhibitio n of return was observed for location-based and identity-based choice responses, although more inhibition was seen in the identity-based res ponses. The results of the third experiment suggested that this larger inhibitory effect may be specific to the covert orienting of reflexiv e attention in response to the sudden appearance of a single periphera l stimulus in the identity tasks. Overall, the results are consistent with the attentional, not the motor, explanation of inhibition of retu rn.