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Abstract:
Abstract: The purpose of the present study was to use
midazolam-induced amnesia to explore the plausibility of the
estimates provided by the process dissociation procedure (PDP;
Jacoby et al., 1993), which is designed to estimate the
contributions of conscious (C) and unconscious (U) processes to
implicit memory performance. In a double-blind, placebo-controlled,
within-subject design with 24 participants, single midazolam doses
were administered intravenously, and word stem completion
performance was used to calculate PDP estimates. Midazolam
administration produced a dissociation between effects on estimates
of C vs. U, such that midazolam decreased C but increased U
relative to placebo. Given that a manipulation which induces
amnesia would not be expected to increase memory performance, these
results add to the accumulating body of evidence suggesting that
PDP estimates are not always theoretically plausible. The finding
that this dissociation occurred following semantic but not
orthographic encoding provides particularly compelling evidence
against the viability of the PDP, given that the within-subject
manipulation of encoding forces interpretation of participants'
strategy to be equated across encoding condition, and that
interpretation of participants' strategy plays a critical role for
Jacoby and colleagues in generating predictions regarding the
expected pattern of PDP estimates. Redundancy may be a more
plausible model of the underlying relationship between C and U than
the PDP's independence model.
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