Event-related potentials as an index of similarity between words and pictures.

This report examines the ERP correlates of processing nontarget stimuli that are conceptually, but not perceptually, similar to a target. In two studies, the P300 component was examined in healthy adults during a multistimulus oddball paradigm. The stimuli were pictures of five objects and their five corresponding names. Participants were required to keep a mental count of number of target presentations. In Experiment 1, the target was the word "globe." Both the word target and the nontarget picture of the globe elicited large P300s, though the P300 to the picture was smaller in amplitude. No other stimulus elicited a prominent P300. In Experiment 2, the target was the picture of the globe, and the word was considered to be the related nontarget. Again, the target elicited a large P300. However, in this case the related nontarget stimulus failed to elicit a P300. The relevance of the data to theories of word/picture processing is discussed.