Early cortical activation indicates preparation for retrieval of memory for faces: an event-related potential study.

Event-related brain potentials (ERPs) were used to investigate the time course of memory processes following the presentation of faces. Following a phase in which subjects were asked to memorize faces presented on a computer screen (study phase) they had to distinguish the previously presented faces from others new to the experiment (test phase). We found that in a time period from 250 to 350 ms after onset of stimulus presentation ERPs show higher negativity for both repeated and novel faces in the test phase compared to the study phase. This situation dependent effect is most pronounced in occipito-temporal regions. We conclude that memory retrieval for faces is a sequential process. The early part of this process constitutes preparation for the retrieval of stored information, and a later part of the process comprises the discrimination between repeated and novel faces.