Oscillatory Correlates of Retrieval-Induced Forgetting in
Recognition Memory

Abstract

Retrieval practice on a subset of previously studied material enhances later memory for practiced material but can inhibit memory for related unpracticed material.
The present study examines the effects of prior retrieval practice on evoked (ERPs) and induced (oscillatory power) measures of electrophysiological activity underlying
recognition of practiced and unpracticed words. Compared to control material, recognition of unpracticed words was characterized by reduced amplitudes of the P2 ERP component
and by reduced early (200-400 ms) oscillatory theta power. The reduction in P2 amplitude was associated with decreased evoked theta power but not with decreased theta phase
locking (PLI). Recognition of unpracticed material was further accompanied by a reduction in occipital gamma power (> 250 ms). In contrast, the beneficial effects of
retrieval practice on practiced words were reflected by larger parietal ERP positivity ( > 500 ms) and by a stronger decrease in oscillatory alpha power in a relatively late time window ( > 700 ms). The results suggest that the beneficial and detrimental effects of
retrieval practice are mediated by different processes. In particular, they suggest that reduced theta (4 – 7 Hz) and gamma (60 – 90 Hz) power reflect the specific effects of
inhibitory processes on the unpracticed material’s memory representation.