Semantic violation effect on object-related action comprehension. N400-like event-related potentials for unusual and...

The present study examined the specific action-sentence compatibility effect. We examined the action representation and semantic processes indexed by event-related potentials (ERPs, N400 effect) when plausible or implausible actions were performed within a dynamic context (video tapes showing a sequence of four action frames). Two different semantic anomalies were reproduced in the final action frame, which consisted of an object that did not have the semantic properties required (functionally unusual) for the action goal (Experiment 1) or an object that was incorrectly used with regard to the instrumental properties required for the target action (Experiment 2). Fifteen participants performed an explicit task to distinguish congruous from incongruous actions for the final action frame. The ERP analysis showed a significant N400-like effect that was frontally distributed in response to incongruous conditions for both Experiment 1 and 2. Similarly, response times (RTs) increased in response to incongruous actions. Nevertheless, a temporo-parietal cortical distribution was more prevalent in the unusual object-action representation (Experiment 1) than in the incorrect object-action representation (Experiment 2). These results may be explained by assuming that in Experiment 1, the relationship between the action and its intentional goals was violated, with a cortical-specific temporo-parietal response, whereas in Experiment 2 the intentional goal to perform the action was not violated. It can be argued that the N400-like effect was similar to the N400, which is generally evoked by linguistic stimuli, and these results suggest that N400 increases as the difficulty in accessing the semantic memory increases.