Brain potentials and repetition effects during encoding and retrieval of words.

Using event-related potentials (ERPs), this study utilized a study-test paradigm to investigate the existence of a common mechanism underlying repeated learning effects during encoding and retrieval. Results showed repeated learning effects occurred in both encoding and retrieval. The effect of encoding, however, appeared earlier and lasted longer than that of retrieval. Furthermore, the effect of implicit retrieval appeared earlier than that of explicit retrieval. The main scalp distributions of the repetition effects related to both encoding and retrieval occurred at parietal and central sites. Both ERP repetition effects manifested significantly larger and positive-going ERP response of repeated words compared with the words' first appearance. The ERP repetition effects support the hypothesis that there is common learning-related automatic processing during encoding and retrieval.