The Impact Of Posthypnotic Amnesia And Directed Forgetting On Implicit And Explicit Memory: New Insights From a Modified Process Dissociation Procedure¹

Abstract

The authors describe a study investigating the relationship between posthypnotic amnesia (PHA) and directed forgetting (DF) and their impact on implicit and explicit memory. This study adopted a recent modification of the process dissociation procedure to accommodate the cross-contamination of memory test performance by implicit and explicit memorial factors. Forty high and 40 low hypnotically susceptible participants were compared in PHA, DF, and control conditions on estimates of voluntary conscious (VCM), involuntary conscious (ICM), and involuntary unconscious memory (IUM) performance. Both groups showed significant decrements in VCM and ICM following instructions for DF, whereas only high susceptibles showed this decrement in the PHA condition; neither DF nor PHA affected IUM. Moreover, there was no relationship between forgetting in PHA and DF. Although both PHA and DF seem to prevent the conscious (i.e., explicit) expression of memorial information while leaving implicit memory intact, the mechanisms underlying these phenomena may nevertheless be different.

Patterns of hypnotic response, revisited

“…For example, we might want to specifically test for divisions in conscious awareness (Hilgard, 1977), as manifested in the hidden observer (Hilgard, Morgan, & Macdonald, 1975; Knox, Morgan, & Hilgard, 1974), trance logic (McConkey, Bryant, Bibb, & Kihlstrom, 1991; Orne, 1959), dissociations between explicit and implicit memory in posthypnotic amnesia (Barnier, Bryant, & Briscoe, 2001; David, Brown, Pojoga, & David, 2000; Kihlstrom, 1980), or dissociations between explicit and implicit perception in hypnotic deafness or blindness (Bryant & McConkey, 1989, 1994). Such dissociations indicate that the percepts or memories in question have been processed, at least to some degree, outside of conscious awareness (Kihlstrom, 2007).…”

Segregation of study items in memory determines the magnitude and direction of directed forgetting

“…The goal of the first experiment was to further test the selective rehearsal account by a new method of probing memory, the global exclusion test. The global exclusion condition forbids the use of any and all words from study (see David, Brown, Pojoga, & David, 2000; Russo & Andrade, 1995, for early attempts using exclusion methods). This condition is the direct opposite of the standard memory condition that invites the participant to use any and all words from study regardless of their tagging (R or F).…”

Elucidating unconscious processing with instrumental hypnosis

“…For example, reflecting the distinction between explicit and implicit memory systems, performances of HHSs on a word association task denote PHA-related priming effects despite significant deficits on explicit recall (Kihlstrom, 1980; David et al, 2000; Barnier et al, 2001). PHA experiments also reveal suppression of conscious access to episodic memory (Kihlstrom, 1997), source memory (Evans and Kihlstrom, 1973; Evans, 1979), and even autobiographical memory (Barnier and McConkey, 1999; Barnier, 2002a,b; Cox and Barnier, 2003; Barnier et al, 2004).…”