An electrophysiological investigation of semantic priming with pictures ofreal objects

Event-related potentials were recorded using color pictures of real objects . Participants made relatedness judgments for pictures that were highly, mo derately, or unrelated to a picture of a preceding prime object (Experiment 1) or object identification decisions for related/easily identified, unrel ated/easily identified, and unrelated/unidentifiable objects preceded by pr ime objects (Experiment 2). Unrelated pictures elicited larger event-relate d potential negativities between 225 and 500 ms than did related pictures, although the first portion of this epoch had a more frontal distribution th an did the later portion. The later epoch differentiated the unrelated from the moderately related and the moderately related from the highly related pictures (Experiment 1), but the early epoch produced differences only betw een the unrelated and related pictures (Experiments 1 and 2). This pattern supports the existence of two separate components, an anterior, image-speci fic N300 and a later: central/parietal amodal N400.