Electrophysiological correlates of feature analysis during visual search

TLDR

ERPs were recorded from young adults during visual search tasks using homogeneous and pop‑out arrays across four experiments that varied target classes. Target pop‑outs elicited enhanced anterior N2, posterior N2, P2, and P3 waves, including a contralateral N2pc subcomponent, whereas the N2 and P1 effects seen in Experiments 1–2 were not fully automatic, supporting guided‑search models.

Abstract

Abstract Event‐related brain potentials (ERPs) were recorded from normal young adults during visual search tasks in which the stimulus arrays contained either eight identical items (homogeneous arrays) or seven identical items and one deviant item (pop‐out arrays). Four experiments were conducted in which different classes of stimulus arrays were designated targets and the remaining stimulus arrays were designated nontargets. In Experiments 1 and 2, both target and nontarget pop‐out stimuli elicited an enhanced anterior N2 wave and a contralaterally larger posterior P1 wave, but Experiments 3 and 4 demonstrated that these components do not reflect fully automatic pop‐out detection processes. In all four experiments, target pop‐outs elicited enlarged anterior P2, posterior N2, occipital P3, and parietal P3 waves. The target‐elicited posterior N2 wave contained a contralateral subcomponent (N2pc) that exhibited a focus over occipital cortex in maps of current source density. The overall pattern of results was consistent with guided search models in which preattentive stimulus information is used to guide attention to task‐relevant stimuli.