Visual search for biological motion: an event-related potential study.

To investigate the neural response to detection of biological motion (BM) surrounded by distractors, event-related potentials (ERPs) were recorded. Scrambled motion with the same velocity vector as the BM but randomized initial starting points was used as the distractor. The number of distractors was varied to control the difficulty of the task. The behavioral data showed that the reaction time increased with the number of distractors. Moreover, the ERP results showed that enhanced negativity was elicited at posterior electrodes contralateral to the location of the BM as with the conventional N2pc-like component, which is related to selection of the target. The increment of reaction time indicated that the attentional process is involved in the detection of BM. Furthermore, the ERP waveforms suggest that, even when detection of the target requires form-from-motion processing, similar neural mechanisms to those involved in conventional visual search tasks were employed here.