The interdependence of spatial attention and lexical access as revealed by early asymmetries in occipito-parietal ERP activity.

One green and one red string of letters were presented on each trial, one to the left and one to the right of fixation. Participants had to attend to a target string defined by color while ignoring the other distractor string. The target string could be a word or a nonword and the task was a delayed lexical decision. The distractor was always a word. When the target was a word, target and distractor were associatively related on half of the trials and not related in the other trials. The event-related potential time-locked to the onset of the letter strings produced an N2pc (a greater negativity at scalp sites contralateral to the target relative to the ipsilateral sites). The N2pc amplitude was reduced when the words were related relative to when they were not related. The results provide direct, online evidence that activation of meaning by visual words is very rapid, and interacts with the mechanisms responsible for the deployment of spatial attention.