Attention switching function of memory-comparison-based change detection system in the visual modality.

To elucidate the attention switching function of a memory-comparison-based change detection system in the visual modality, the effects of task-irrelevant infrequent stimulus-size decrements that engaged memory-comparison-based change detection as well as stimulus-size increments that engaged memory-comparison-based change detection and refractoriness-based rareness detection on behavioral and event-related brain potential (ERP) measures were assessed using the distraction paradigm. Both size increments and size decrements caused distraction in forced-choice task performance, which was mirrored by a posterior negativity (peaking at around 240-260 ms, posterior N2) and a broad positivity (420-460 ms, P3a) that reflected attentional capture. Preceding these effects, size increments elicited a posterior negativity (120-140 ms, change-related negativity), while size decrements elicited a posterior positivity (140-160 ms, change-related positivity) and an anterior positivity (160-180 ms, frontal positivity). Taken together, these results indicate an attention switching function of a memory-comparison-based change detection system in the visual modality, which is most probably indexed by change-related positivity.