The role of state-dependent memory in "red-outs"

Addictive drugs modify neurogenesis, synaptogenesis and synaptic plasticity to impair memory formation through neurotransmitter imbalances and signaling dysfunction

Drug abuse changes neurophysiological functions at multiple cellular and molecular levels in the addicted brain. Well-supported scientific evidence suggests that drugs negatively affect memory formation, decision-making and inhibition, and emotional and cognitive behaviors. The mesocorticolimbic brain regions are involved in reward-related learning and habitual drug-seeking/taking behaviors to develop physiological and psychological dependence on the drugs. This review highlights the importance of specific drug-induced chemical imbalances resulting in memory impairment through various neurotransmitter receptor-mediated signaling pathways. The mesocorticolimbic modifications in the expression levels of brain-derived neurotrophic factor (BDNF) and the cAMP-response element binding protein (CREB) impair reward-related memory formation following drug abuse. The contributions of protein kinases and microRNAs (miRNAs), along with the transcriptional and epigenetic regulation have also been considered in memory impairment underlying drug addiction. Overall, we integrate the research on various types of drug-induced memory impairment in distinguished brain regions and provide a comprehensive review with clinical implications addressing the upcoming studies.

Unethical amnesia responds more to instrumental than to hedonic motives

Using large-scale incentivized online experiments, we tested two possible origins of individuals’ forgetting about their past cheating behavior in a mind game. We found that purely hedonic considerations, such as the maintenance of a positive self-image, are not sufficient to motivate unethical amnesia, but the addition of an instrumental value to forgetting triggers such amnesia. Individuals forget their past lies more when amnesia can serve as an excuse not to engage in future morally responsible behavior. These findings shed light on the interplay between dishonesty and memory and suggest further investigations of the cost function of unethical amnesia. A policy implication is that improving ethics requires making unethical amnesia more difficult for individuals.

Humans care about morality. Yet, they often engage in actions that contradict their moral self. Unethical amnesia is observed when people do not remember or remember less vividly these actions. This paper explores two reasons why individuals may experience unethical amnesia. Forgetting past unethical behavior may be motivated by purely hedonic or affective reasons, such as the willingness to maintain one’s moral self-image, but also by instrumental or strategic motives, in anticipation of future misbehavior. In a large-scale incentivized online experiment (n = 1,322) using a variant of a mind game, we find that hedonic considerations are not sufficient to motivate the forgetting of past cheating behavior. This is confirmed in a follow-up experiment (n = 1,005) in which recalls are elicited the same day instead of 3 wk apart. However, when unethical amnesia can serve as a justification for a future action, such as deciding on whether to keep undeserved money, motivated forgetting is more likely. Thereby, we show that motivated forgetting occurs as a self-excuse to justify future immoral decisions.

The Detection of Malingered Amnesia: An Approach Involving Multiple Strategies in a Mock Crime

The nature of amnesia in the context of crime has been the subject of a prolonged debate. It is not uncommon that after committing a violent crime, the offender either does not have any memory of the event or recalls it with some gaps in its recollection. A number of studies have been conducted in order to differentiate between simulated and genuine amnesia. The recognition of probable malingering requires several inferential methods. For instance, it typically involves the defendant's medical records, self-reports, the observed behavior, and the results of a comprehensive neuropsychological examination. In addition, a variety of procedures that may detect very specific malingered amnesia in crime have been developed. In this paper, we investigated the efficacy of three techniques, facial thermography, kinematic analysis, and symptom validity testing in detecting malingering of amnesia in crime. Participants were randomly assigned to two different experimental conditions: a group was instructed to simulate amnesia after a mock homicide, and a second group was simply asked to behave honestly after committing the mock homicide. The outcomes show that kinematic analysis and symptom validity testing achieve significant accuracy in detecting feigned amnesia, while thermal imaging does not provide converging evidence. Results are encouraging and may provide a first step towards the application of these procedures in a multimethod approach on crime-specific cases of amnesia.

Testing Claims of Crime-Related Amnesia

Many violent offenders report amnesia for their crime. Although this type of memory loss is possible, there are reasons to assume that many claims of crime-related amnesia are feigned. This article describes ways to evaluate the genuineness of crime-related amnesia. A recent case is described in which several of these strategies yielded evidence for feigned crime-related amnesia.

Let's use those tests! Evaluations of crime-related amnesia claims

Suspects awaiting trial often claim that they cannot remember important parts of their violent crimes. It is not unusual that forensic experts readily accept such claims and interpret them in terms of dissociative amnesia or, more specifically, a "red-out". This interpretation hinges on the assumption that heightened levels of stress implicated in violent crimes interfere with memory. We argue that the notion of red-out is a priori not plausible and that alternative interpretations-primarily malingering and substance-induced organic amnesia-should be considered and ruled out first before concluding that memory loss is dissociative in nature. We illustrate our point with four cases that superficially have the contours of red-out tragedies. We believe that, in such cases, neuropsychological tests and/or psychopharmacological information on dose-response relationships can assist forensic experts to exclude malingering or substance-induced amnesia. There is no reason for not using tests and tools from neuropsychology and psychopharmacology.

Evaluating amnesia for criminal behavior: a guide to remember

This article provides a guide that is important to remember in evaluating a criminal defendant's amnesia claim. Important concepts to understand regarding memory formation, memory systems, proposed causes of amnesia, reasons why amnesia claims may be true or false, and important strategies to implement as part of the evaluation process are reviewed. Structured assessment approaches are critical components of amnesia evaluations and generally require detailed questioning, review of collateral records, medical and neurologic workups, psychological testing, neuropsychological testing, and specific malingering assessments.

A comparison of memory for homicide, non-homicidal violence, and positive life experiences

Defendants commonly claim amnesia for their criminal actions especially in cases involving extreme violence. While some claims are malingered or result from physiological factors, other cases may represent genuine partial or complete amnesia resulting from the psychological distress and/or extreme emotion associated with the perpetration of the crime. Fifty Canadian homicide offenders described their memories of their homicide, a non-homicide violent offense, and their most positive adulthood life experience. Self-reported and objective measures of memories for these events revealed that homicides were recalled with the greatest level of detail and sensory information. Although dissociative tendencies were associated with a self-reported memory loss, objective measures of memory quality did not reflect this perceived impairment, suggesting a failure of meta-memory. Recollections of positive life events were superior to those of non-homicidal violence, possibly due to greater impact and meaning attached to such experiences. Findings suggest that memory for homicide typically is enhanced by the powerful emotion associated with its perpetration.

Claims of amnesia for criminal offenses: psychopathology, substance abuse, and malingering

The forensic psychiatric examiner often encounters defendants who deny memory for their offense. Past research proposes a variety of factors to account for offense amnesia. To date there have been few systematic studies of offense amnesia in relation to psychiatric diagnosis, either alone or in combination with other known factors such as substance use and malingering. We studied 53 pretrial felony defendants who had been referred for psychiatric examination; 40% claimed amnesia for their offense. Examinees with psychotic disorders in general, and schizophrenia in particular, were relatively less likely to claim amnesia than were examinees with other diagnoses. Substance use at the time of the offense and associated substance use disorder diagnoses were positively associated with offense amnesia. Malingering diagnosed by general clinical criteria was a poor predictor of amnesia claims. These data suggests that two prominent reasons for referral for forensic psychiatric evaluation include the presence of psychotic symptoms and claims of amnesia for the offense.

Acute consolidation stress enhances reality monitoring in healthy young adults

Source monitoring refers to cognitive processes involved in making attributions about the origins of memories, knowledge, and beliefs. One particular type of source monitoring with ample practical significance is reality monitoring, i.e., the ability to discriminate between internally vs. externally generated memories. Abundant evidence indicates that exposure to acute stress enhances declarative memory consolidation. To date, no study has looked at whether exposure to acute stress during the consolidation phase may promote reality monitoring performance. The authors examined this by administering cold pressor stress (CPS) or a control procedure to participants (N = 80) after they had either performed or only imagined performing simple motor acts, and assessing reality monitoring 24 h later. When compared with the control condition, CPS significantly elevated salivary free cortisol concentrations and enhanced reality monitoring. Stress-induced cortisol responses, however, were found not to be related to improved reality monitoring performance. Our findings are consistent with the view that post-learning stress hormone-related activity may modulate source memory consolidation.

What violent offenders remember of their crime: empirical explorations

Little systematic evidence is available about how violent offenders remember and think about their violent crimes. The general aim of this article is to selectively review a range of different 'types' of memory disturbance and their risk factors, in an attempt to draw together different strands of research concerning memories of offending that might usefully be considered together for clinical purposes. A selective review of psychiatric or psychological studies related to amnesia, intrusive memories, posttraumatic stress disorder (PTSD), ruminations, and pleasurable memories was performed. The body of research on amnesia in relation to violent crime is relatively small and is subject to significant limitations. The empirical base of studies identifying intrusive memories arising from violent crime is also very limited, with no previous published study primarily focusing on description of the form and content of intrusive memories related to acts of violence in a population of violent offenders. A small number of studies have investigated PTSD directly arising from the commission of a violent or sexual crime, in those with mental illness. No published studies that investigated the presence of ruminations related to violent offending were identified. No systematic comparative studies were identified that described the form and content that positive memories of non-sexual violence might take. Relevant phenomenological reports from extreme populations raise concerns about selection bias. A memory-based approach to eliciting descriptions of violent offending may elicit clinical information relevant to violence risk assessment and therapeutic interventions within forensic settings.

Dissociation and violence: a review of the literature

Violent acts are sometimes committed by people who do not normally appear violent or aggressive. This simple observation and others have led some to speculate about a relationship between dissociation and violence. However, no systematic review of the literature has so far been published. To address this gap, studies assessing the prevalence of dissociation among violent individuals, and violence among highly dissociative persons, are reviewed. Possible links between dissociation and violent behavior are explored. It is concluded that dissociation predicts violence in a wide range of populations and may be crucial to an understanding of violent behavior. There is a clear need, however, for large scale, well-designed studies using reliable structured instruments in a number of areas reviewed. Recommendations for clinical applications include the routine screening of offenders for dissociative disorders and adequate consideration of dissociation and dissociative disorders in the development and implementation of violence treatment and prevention programs.

Absolut memory distortions: alcohol placebos influence the misinformation effect

Can the simple suggestion that you have consumed alcohol affect your memory for an event? Alcohol placebos affect social behaviors but not nonsocial ones, and have not previously been shown to affect memory. We investigated the effect of alcohol placebos using materials that revealed both the social and the nonsocial influences of memory Subjects drank plain tonic water, but half were told it was a vodka and tonic; then all subjects took part in an eyewitness memory experiment. Subjects who were told they drank alcohol were more swayed by misleading postevent information than were those who were told they drank tonic water, and were also more confident about the accuracy of their responses. Our results show that the mere suggestion of alcohol consumption may make subjects more susceptible to misleading information and inappropriately confident. These results also provide additional confirmation that eyewitness memory is influenced by both nonsocial and social factors.

Disagreement about the occurrence of male-to-female intimate partner violence: a qualitative study

This work explored the reasons underlying inter-partner disagreement about the occurrence of intimate partner violence (IPV). Research indicates that partners often do not agree about episodes of conflict in their relationship. We conducted interviews with 48 women and men with and without histories of IPV to investigate this lack of agreement. Participant responses were analyzed and themes were identified about why men and women disagree about episodes of conflict. The main results indicate that participants think women and men remember differently; women remember more than men, both choose what they want to remember, and both remember that they were right in the conflict. This work contributes to understanding the disagreement that occurs between partners. Many of these findings have never been suggested by other IPV researchers. The broad-reaching implications of this study include improvement in the accuracy of measuring IPV.

Memory for murder. A psychological perspective on dissociative amnesia in legal contexts

There is currently a complex and inconsistent state in the law relating to dissociation and dissociative amnesia (McSherry, 1998). Although dissociative amnesia in defendants is relevant to both competency to stand trial and criminal responsibility in principle, courts have typically assumed a skeptical stance toward such claims in practice. However, there is considerable evidence from both nonoffender and offender populations to support the validity of dissociative amnesia in defendants. Further, there is information available to aid in the evaluation of amnesia, such as the quality of the report itself and characteristics of the person reporting the amnesia (e.g., psychopathy). When consideration is given to the legal response to reports of dissociative amnesia by complainants, the situation becomes even more complex. While some courts have rejected recovered memory evidence, others have convicted defendants of historical offenses based on such evidence. In some cases, judges have argued that jurors should be left to decide on the validity of recovered memories based on their common sense and experience. The uncritical acceptance of the validity of repressed memories in complainants by many courts stands in stark contrast to the response to claims of amnesia from defendants. It seems apparent that the courts need better guidelines around the issue of dissociative amnesia in both populations. We think that the increasing scientific understanding of memory in the past decade (see Schacter, 1999) can meaningfully contribute to the development of such guidelines. Responsible, nonpartisan expert testimony from mental health professionals would be one step in the direction of rectifying the current state of law in regards to dissociation.