After the P3: Late executive processes in stimulus categorization

摘要: Two experiments examined the hypothesis that dual systems of stimulus evaluation for categorization can be observed in event-related potentials: one whose duration is indexed by latency P3 component, and a second evident later frontal potential. Subjects categorized artificial animals "two out three" rule. Stimuli with two visual features their own category feature different (i.e., near boundary between categories) elicited very prolonged reaction times as compared to stimuli three from single category. This response time (RT) delay was not accompanied delayed P3, suggesting only first pass evaluation. The near-boundary more positive potentials than far-boundary at prefrontal frontotemporal sites, secondary stage triggered when detection or simple conjunctions insufficient support correct decision. potential sensitive difficulty opposite polarity previously manipulations working memory. roles executive processes memory tasks are discussed.