RP and N400 ERP components reflect semantic violations in visual processing of human actions.

Event-related brain potentials (ERPs) were used to investigate the visual processing of actions belonging to the typical human repertoire. Two hundred and sixty coloured pictures representing persons differing in number, age and gender, engaged in simple actions, were presented to 23 right-handed students. Perception of meaningful actions (e.g., young woman trying shoes in shop) was contrasted with perception of actions lacking an understandable goal (e.g., businesswoman balancing on one foot in desert). The results indicated early recognition of comprehensible behaviour in the form of an enhanced posterior "recognition potential" (RP) (N250), which was followed by a larger negativity (N400) in response to incongruent actions. The results suggest that incoming visual information regarding human gestures is processed similarly to linguistic inputs from a conceptual point of view, thus eliciting a posterior RP when the action code is visually recognized and comprehended, and a later N400 when the action is not recognized or is difficult to integrate with previous knowledge.