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Abstract:
A central issue in research of directed forgetting is whether
the differential memory performance for remember and forget items
is due to differential encoding or retrieval inhibition of forget
items. In this study we used event-related potentials (ERPs) to
examine this issue. In Experiment 1 subjects were instructed to
remember or forget words by means of a cue presented after each
word. ERPs recorded from 61 scalp sites in the test phase revealed
phasic frontal and parietal old/new effects for remember items,
whereas forget items elicited only a frontal effect. Moreover, both
items evoked a late right frontal positive slow wave being more
pronounced for forget items, suggesting that those items are
associated with a larger amount of post-retrieval processes. In
Experiment 2 the same single word cueing method and the same
stimulus material were used. Memory encoding was manipulated by
cueing subjects to process the words either deeply or shallowly.
Both, deeply and shallowly encoded words elicited phasic frontal
and parietal old/new effects followed by a right frontal positive
slow wave. However, in contrast to remember and forget items these
effects differed only quantitatively. Taken together, these results
suggest that differential encoding alone cannot account for the
effects of directed forgetting. They are more consistent with the
view that items followed by an instruction to forget become
inhibited and less accessible, and thus are more difficult to
retrieve.
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