Effects of attention and semantic relation on event-related potentials in a picture-word naming task

The interactive effects of attention and semantic relation on event-related potential (ERP) waveforms were examined during a naming task in which the physical stimulus array was the same across conditions, superimposed pictur e-word pairs were presented in which the meaning of the words and pictures was congruent, semantically associated, or incongruent. In separate conditi ons, participants named words or pictures while ignoring the other stimulus . When words were attended, the superimposed pictures modulated the amplitu de of P240 waves at posterior sites compared with when words were presented individually. but had no effect on N450 waves. In contrast, when pictures were attended to, the superimposed incongruent words elicited larger amplit ude N450 waves at anterior sites than did congruent words or individually p resented pictures. These effects affirm the independent processing of words and pictures during attention and are consistent with automatic and contro lled processing of words and pictures. respectively. They also illustrate t he endogenous nature of these late ERP waves. (C) 2000 Elsevier Science B.V . All rights reserved.