The Amplitude of N2pc Reflects the Physical Disparity Between Target Item and Distracters

The N2pc component of the event-related potentials is assumed to indicate attentional filtering processes during visual search tasks. In this study, we investigated the effects of physical disparity between a target stimulus and distracter stimuli and discrimination difficulty of the target item, on N2pc component by recording event-related potentials (ERPs) while subjects completed a visual search task. In the visual search task, we presented a round array of stimuli and manipulated the color disparity between the target and distracters and the discriminative difficulty of the target's form. The results showed that higher amplitude of N2pc was elicited in the high color disparity condition compared to the low disparity condition. However, no significant effect was found for the discriminative difficulty. The results suggested that the N2pc component could be modulated by the physical disparity between the target item and the distracters in the searching processes, which most likely reflects allocation of attention to select an object based on the perceptual saliency of that object.