Target discrimination delays attentional benefit for grouped contexts: An ERP study

Searching a target was shown to be facilitated when embedded in a homogeneous compared to a heterogeneous context. This study investigated extended attention deployment after visual search for a target that observers had to discriminate in contexts of varying heterogeneity. Results showed more efficient attention deployment towards targets in homogeneous contexts as evident in higher accuracy and larger N2pc amplitudes than in random contexts. RTs to subsequently presented probes were shorter and a larger posterior positivity was observed in the ERP when probes were presented at the target location compared to other locations. This on-target advantage was larger for homogeneous contexts at ISIs of 90ms, but not for shorter (30ms) or longer (150ms) ISIs. These results show that visual search tasks induce an accelerated attention deployment after homogeneous contexts, however with a delay after target discrimination compared to less demanding target detection.