N400 involvement in the processing of action sequences.

Understanding others' sequences of action is a fundamental aspect of human movement and is the key to detecting goal directed behavior and intentional actions. Human action contains semantic information whereby logical chains of events are entirely dependent on the sequence in which they are performed. The sequential nature of action ensures that an observing individual anticipates the conclusion of a viewed action. This experiment reports on the results of 15 participants who viewed videos of an actress performing actions. Half the stimuli contained an anticipated conclusion to the action whereas half did not. Results from the passive viewing of stimuli depicting eating actions indicated an increased N400 response over frontal, central and parietal regions when viewing the unanticipated conclusions of the actions as compared with the amplitude for the anticipated condition. These results show that (1) neural systems exist to rapidly discern semantic information in actions, and (2) the N400 component, which predicts semantic information in language, also anticipates information within goal directed action.