Temporal dynamics of activation and suppression in a spatial Stroop task: A distribution analysis on gaze and arrow targets.

Directional judgments of an arrow became slower when the direction and location were incongruent in a spatial Stroop task (i.e., a standard congruency effect). In contrast, gaze judgments were slower when they were congruent (i.e., a reversed congruency effect). This study examined the reaction time (RT) distribution of interference effects in a spatial Stroop task to clarify the temporal characteristics of the standard congruency effect, which is known to be reversed for social targets, such as gaze direction. Participants responded to laterally presented targets (i.e., arrows, gaze, fish-only, and fish with mosaic) while ignoring their location. The standard congruency effect of arrows decreased as the overall RT increased, reflecting the temporal decay of automatically activated task-irrelevant codes (i.e., location). Critically, the reversed congruency effect of gaze increased as the overall RT increased. This result supports the dual-stage hypothesis and reflects the late-arriving selective inhibition of task-irrelevant codes. Similar results were replicated in Experiment 2, in which we manipulated the complexity of the backgrounds of nonsocial targets and in the reanalysis of existing data. These findings imply that the interplay between task-irrelevant activation and subsequent inhibition is modulated by specific stimulus characteristics, influencing spatial response selection.