Coherence in general and personal semantic knowledge: functional differences of the posterior and centro-parietal N400 ERP component.

A growing body of scientific literature investigated the difference between general and personal semantic knowledge. In contrast to general world knowledge, personal semantics comprises highly individual knowledge about oneself. The present study aimed to differentiate processes of integration into personal as opposed to general semantic knowledge. For that purpose, participants were presented with pictures of themselves (Self-condition) or unknown persons (Other-condition) superimposed on a congruent or incongruent background. We hypothesized that self-referential processing is based on automatic retrieval of personal information as opposed to the processing of unknown persons, which requires voluntary, i.e., strategic, attention demanding processing. The topography of the N400 effect varied as a function of the type of semantic knowledge. We found a centro-parietal N400 effect within the Self-condition and a posterior effect within the Other-condition. The voluntary integration of facial expressions of unknown persons within the Other-condition was, furthermore, indexed by an N170 effect. The unresolved tension in personal semantics was reflected by the N500. Our study thus provides new impulses for interpretation of the N400's functional properties and extends our knowledge about the N500. Implications for the functional properties of the self as an organizational structure are discussed.