Spatial and temporal organization of episodic and semantic processes revealed by event-related potentials to unfamiliar faces.

This study investigated whether the semantic and episodic processes underlying the old/new effect can be dissociated by analyzing the spatial and temporal characteristics of event-related potentials (ERPs) evoked by unfamiliar face stimuli during direct and indirect memory tests. The ERP old/new effects obtained included three components. First, the classical posterior component, present in both tasks, which was thus interpreted as reflecting changes in the automatic activation of semantic representation. Second, an earlier frontal component, present in the direct test only, which was seen a consequence of the building of a contextual representation of presented items formed of a conjunction of elements stored in semantic memory. Third, a late right-temporal component, in the direct test, which was related to the integration of this conjunction into a unitized representation of the presented stimuli.