Implanting rich autobiographical false memories: Meta-analysis for forensic practice and judicial judgment making

Objective

The implanting of rich autobiographical false memories is crucial for judicial decision-making, and the forensic evaluation of a testimony. In order to assess this issue, a meta-analytical review of the probability of implanting rich autobiographical false memories was performed.

Method

A total of 30 primary studies analysing the probability of implanting rich autobiographical false memories were retrieved. Random-effects meta-analyses correcting the effect size for sampling error were performed.

Results

The results revealed a significant, positive, generalizable (the lower limit for the 80% credibility value was d = 1.13), and more than large mean effect size (d = 1.43[1.33, 1.53]) for the implanting of false memory. The moderating effects of stimulus type showed that the effect of the probability of implanted false memory was significantly higher in experienced events (d = 2.03[1.63, 2.43]) than in false narratives (d = 1.35[1.23, 1.47]), and in doctored photographs (d = 1.29[1.06, 1.52]). A similar effect for memory implantation was observed in both the underage (d = 1.44[1.29, 1.59]), and in adults (d = 1.36[1.22, 1.50]). The moderator techniques for implanting false memories revealed a significantly lower probability of implanting false rich memory with non-directive instructions (d = 0.90[0.53, 1.27]) than with guided imagery (d = 1.45[1.32, 1.58]), or with pressure to answer (d = 1.56[1.17, 1.95]) instructions. The event emotional valence moderator exhibited the same effect for positive (d = 1.27[1.09, 1.45]) and negative valence events (d = 1.30[1.17, 1.43]).

Conclusions

The implications of the results for forensic testimony evaluation, police interrogations, and judicial cross-examination are discussed.

Suppression and Memory for Childhood Traumatic Events: Trauma Symptoms and Non-Disclosure

Self-reported lost memory of child sexual abuse (CSA) can be mistaken for "repressed memory." Based on our longitudinal studies of memory and disclosure in child maltreatment victims who are now adults, we discuss findings relevant to "repressed memory cases." We examined relations between self-report of temporarily lost memory of CSA (subjective forgetting) and memory accuracy for maltreatment-related experiences (objective memory). Across two studies involving separate samples, we find evidence for memory suppression rather than repression: (1) Most adults who claimed temporary lost memory of CSA reported memory suppression and clarified that they could have remembered the event if asked; (2) subjective forgetting was positively associated with accurate objective memory for maltreatment-related experiences. Subjective forgetting was also related to increased adult trauma symptoms and related to childhood non-disclosure of CSA. Moreover, trauma-related psychopathology mediated the relation between non-disclosure and subjective forgetting. Implications for psychological theory and repressed memory cases are discussed.

The acute effects of classic psychedelics on memory in humans

RATIONALE

Memory plays a central role in the psychedelic experience. The spontaneous recall and immersive reliving of autobiographical memories has frequently been noted by researchers and clinicians as a salient phenomenon in the profile of subjective effects of classic psychedelic drugs such as psilocybin, LSD, and ayahuasca. The ability for psychedelics to provoke vivid memories has been considered important to their clinical efficacy.

OBJECTIVE

This review aims to examine and aggregate the findings from experimental, observational, and qualitative studies on the acute modulation of memory by classic psychedelics in humans.

METHOD

A literature search was conducted using PubMed and PsycInfo as well as manual review of references from eligible studies. Publications reporting quantitative and/or qualitative findings were included; animal studies and case reports were excluded.

RESULTS

Classic psychedelics produce dose-dependently increasing impairments in memory task performance, such that low doses produce no impairment and higher doses produce increasing levels of impairment. This pattern has been observed in tasks assessing spatial and verbal working memory, semantic memory, and non-autobiographical episodic memory. Such impairments may be less pronounced among experienced psychedelic users. Classic psychedelics also increase the vividness of autobiographical memories and frequently stimulate the recall and/or re-experiencing of autobiographical memories, often memories that are affectively intense (positively or negatively valenced) and that had been avoided and/or forgotten prior to the experience.

CONCLUSIONS

Classic psychedelics dose-dependently impair memory task performance but may enhance autobiographical memory. These findings are relevant to the understanding of psychological mechanisms of action of psychedelic-assisted psychotherapy.

Reports of Recovered Memories in Therapy in Undergraduate Students

Psychologists have debated the wisdom of recovering traumatic memories in therapy that were previously unknown to the client, with some concerns over accuracy and memory distortions. The current study surveyed a sample of 576 undergraduates in the south of the United States. Of 188 who reported attending therapy or counselling, 8% reported coming to remember memories of abuse, without any prior recollection of that abuse before therapy. Of those who reported recovered memories, 60% cut off contact with some of their family. Within those who received therapy, those who had a therapist discuss the possibility of repressed memory were 28.6 times more likely to report recovered memories, compared to those who received therapy without such discussion. These findings mirror a previous survey of US adults and suggest attempts to recover repressed memories in therapy may continue in the forthcoming generation of adults.