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Abstract:
The process dissociation procedure (PDP) estimates conscious
(C) and automatic (A) memory processes by comparing performance
when subjects are to respond with either an old item (inclusion
task) or a new item(exclusion task). C can be estimated by
subtracting an incorrect response of an old item during the
exclusion task (i.e., due to A when C fails) from a correct
response of an old item during the inclusion task (i.e., due to C
and A). The effect of study-test lag on C and A were investigated
while recording event-related potentials (ERPs). In the inclusion
and exclusion tasks, lags of 0-32 items occurred between study and
test (letter insertion). The only significant behavioural effect of
lag was seen as an increased C when the lag was 0. In the ERPs,
this immediate repetition effect was associated with a greater
parietal positivity and less frontal negativity at 380 ms.
Subtracting waveforms according to PDP, in order to obtain an index
of C, showed a parietal positivity with maximum amplitude at 630
ms. The lack of lag-effect on this peak suggests that the
behavioural effect of immediate repetition may represent processes
distinct from conscious memory. A parietal positivity was seen at
380 ms for responses of old items in the exclusion task. Since
there was no associated frontal negativity, this peak may represent
A, separate from overlapping immediate repetition effects.
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