Alcohol-induced retrograde facilitation renders witnesses of crime less suggestible to misinformation

Acute alcohol intoxication and alcohol expectancy effects on women's memory for consensual and non-consensual sexual activity

Objective

To test whether acute alcohol intoxication and alcohol expectancy affects how accurately women remember consensual and non-consensual sexual activity that occurred during an interactive hypothetical dating scenario.

Design

A balanced placebo randomized study that varied alcohol dose (mean Breath Alcohol Content; BrAC = 0.06%) and alcohol expectancy prior to participants encoding a hypothetical interactive rape scenario was implemented. Participants could elect to consent to sexual activity with a male partner in the hypothetical scenario. If they stopped consenting, non-consensual sexual intercourse (i.e., rape) was described. Seven days later, participants' memory for consensual and non-consensual sexual activity in the scenario was tested.

Main outcome measures

Memory accuracy, confidence, and feelings of intoxication.

Results

A total of 90 females (M age = 20.5, SD = 2.2) were tested regarding their memory accuracy for the consensual and non-consensual sexual activities in the scenario. A multi-level logistic regression predicting memory accuracy for the perpetrator's behaviors during the rape indicated no effect of alcohol intoxication. However, a main effect of alcohol expectancy was found, whereby participants who expected to consume alcohol, compared to those who did not, recalled the perpetrator's behaviors during the rape more accurately. A second regression predicting memory accuracy for consensual sexual activity found no main effects for alcohol intoxication or alcohol expectancy. Participants recalled consensual sexual activity with a high degree of accuracy. Calibration analyses indicated that accuracy increased with confidence level, regardless of intoxication level or alcohol expectancy condition, but that women tended to be overconfident in general.

Conclusion

This study provides an important test of how accurately women remember consensual and non-consensual sexual activities. The accuracy of this information is important for forensic medical examinations and police investigations following an allegation of sexual assault. Increased memory accuracy was found for offence details when participants expected to consume alcohol, suggesting there may be important differences in attentional processes (e.g., hypervigilance) depending on whether threat is present. Further research is necessary to investigate memory for sexual violence in real-world settings and to test methods for ascertaining the most complete and reliable accounts.

The impact of post-encoding alcohol consumption on episodic memory recall and remember-know responses in heavy drinkers

Introduction

People often consume alcohol following trauma, particularly in response to distressing memories. To date, little is known about how post-encoding alcohol consumption influences episodic memory recall for negative events. Understanding these effects may help to improve support for trauma victims - for example, witnesses and victims of crimes.

Methods

We tested 60 participants who self-described as heavy drinkers. After watching an analog trauma film, half were allocated to consuming a moderate dose of alcohol (Alcohol-Exposed group), while half received a placebo drink (Placebo-Control group). Immediately and after a one-week delay, participants recalled the event via free and cued recall tasks. Participants also gave remember-know responses and confidence ratings, elucidating alcohol's effect on experiential memory.

Results

Free recall performance was similar for the Alcohol-Exposed group and the Placebo-Control group during Sessions 1 and 2. The Alcohol-Exposed group benefitted more from the delayed repeated retrieval attempt. For the cued recall task, the Alcohol-Exposed group provided more "Do not Know" responses compared to the Placebo-Control group in both sessions. For the Alcohol-Exposed group only "Correct Know" responses increased from Session 1 to 2. Although memory performance improved across sessions, confidence levels decreased from Session 1 to 2 in the Alcohol-Exposed group.

Discussion

Post-encoding alcohol consumption appears to impact immediate episodic memory retrieval; however, this effect is only temporary in nature. No evidence was found that alcohol primarily reduces remembering responses. Much like previous findings focusing on pre-encoding alcohol consumption (Hagsand et al., 2017), current findings suggest that providing individuals who drank alcohol after witnessing an incident with a delayed repeated retrieval attempt can lead to more complete and accurate testimonies.

No evidence that low levels of intoxication at both encoding and retrieval impact scores on the Gudjonsson Suggestibility Scale

RATIONALE

It is not uncommon for police to question alcohol-intoxicated witnesses and suspects; yet, the full extent to which intoxication impacts individuals' suggestibility in the investigative interviewing context remains unclear.

OBJECTIVE

The present study sought to measure the effect of alcohol-intoxication on interviewee suggestibility by implementing a standardized suggestibility test with participants whose intoxication-state was the same at both encoding and recall.

METHODS

We randomly assigned participants (N = 165) to an intoxicated (mean breath alcohol level [BrAC] at encoding = 0.06%, and BrAC at retrieval = 0.07%), active placebo (participants believed they consumed alcohol but only consumed an insignificant amount to enhance believability), or control (participants knowingly remained sober) group. An experimenter then implemented the Gudjonsson Suggestibility Scale (GSS), which produced free recall outcomes (number of correct details and memory confabulations) and suggestibility outcomes (yielding to leading questions and changing answers in response to negative feedback from the experimenter).

RESULTS

Intoxicated participants recalled fewer correct details than did placebo and control participants but did not make more confabulation errors. No effects of intoxication on suggestibility measures emerged.

CONCLUSIONS

Moderately intoxicated interviewees may not be more suggestible during investigative interviews than sober interviewees. However, before concrete evidence-based policy recommendations are made to law enforcement, further research is needed examining the effects of alcohol on suggestibility in conditions that are more reflective of the legal context.

The effect of acute alcohol consumption on meal memory and subsequent food intake: Two laboratory experiments

Altering the quality of episodic meal memories has been shown to affect subsequent food intake. Acute alcohol consumption disrupts memory formation and produces short-term overeating. In two studies, we investigated whether alcohol consumption can affect meal-related memories and later food intake. Study 1 (N = 60, 50% male) investigated how consumption of an alcoholic drink (0.5 g/kg) prior to consumption of a lunch meal affected meal memory of that lunch, and later food intake, compared with a placebo-alcohol. Findings revealed that alcohol consumption did not impair meal memory, and did not affect subsequent food intake. Study 2 (N = 72, 50% male) investigated whether, due to alcohol's retrograde facilitation effect (the enhancement of recall due to reduced interference at the point of exposure) consuming alcohol after consumption of a lunch meal could enhance meal memory, compared with when consumed before a lunch meal (both a dosage of 0.6 g/kg), and compared with consumption of a soft drink. Contrary to prediction, alcohol consumed after a lunch meal did not significantly increase meal memory. But, certain types of meal memory were impaired when alcohol was consumed before the meal, compared with consumption of a soft drink. Subsequent food intake did not differ between conditions. Taken together, findings suggest that alcohol intoxication can impair some forms of meal memory recall, likely due to disruption of memory formation during the encoding phase. However, there was no evidence that this impairment contributes towards alcohol-induced overeating.

Hazy memories in the courtroom: A review of alcohol and other drug effects on false memory and suggestibility

Alcohol and other psychoactive drugs are oftentimes implicated in legal cases. A pertinent question herein is whether such substances might adversely affect testimonies of victims, eyewitnesses, or suspects by propelling the formation of false memory and increasing susceptibility to suggestion. In the current review, we amassed all available evidence on the effects of intoxication on false memory formation and suggestibility, including the substances alcohol, benzodiazepines, cannabis, stimulants, hallucinogens, and antipsychotics. Our review indicated that alcohol and cannabis under certain conditions increased the susceptibility to false memories and/or suggestion with effect sizes ranging from medium to large. When intoxicated during an event, alcohol is most likely to increase this susceptibility at high intoxication levels or after a delay, whereas cannabis exerts detrimental effects during acute intoxication but not necessarily once sober. For other substances, ecologically valid research separating different memory phases is needed. Overall, differences between substances regarding false memory effects exist, suggesting that a nuanced approach is needed when dealing with intoxicated individuals in a legal context.

The intoxicated co-witness: effects of alcohol and dyadic discussion on memory conformity and event recall

RATIONALE

Co-witness discussion is common and often witnesses are under the influence of alcohol. As such, it is important to understand how such factors may influence eyewitness testimony.

OBJECTIVES

We combined a co-witness memory paradigm with an alcohol administration paradigm to examine the influence of alcohol and dyadic discussion on remembering a mock crime.

METHODS

Intoxicated and sober dyads discussed a previously seen video, whilst in a control condition sober and intoxicated individuals recalled the event on their own. Unknown to the dyads, each discussion partner saw a different version of the video including unique details not present in the other video version. All participants then engaged in a second individual recall attempt.

RESULTS

Dyads were more likely to recall misleading details in their individual recall attempts compared to the control group. Intoxicated and sober dyads were equally likely to report misleading information. Alcohol intoxication had no negative impact on individuals' ability to correctly identify the source of their responses. Intoxicated participants recalled fewer details under free recall conditions. Alcohol had a detrimental effect on participants' confidence in their free recall accounts.

CONCLUSIONS

Possible alcohol-related and social-cognitive mechanisms are discussed which may contribute to the current findings as well as applied implications for interviewing intoxicated witnesses.

Improving intoxicated witness recall with the Enhanced Cognitive Interview

RATIONALE

Witnesses and victims typically provide the central leads in police investigations, yet statistics from past research indicates in many instances these individuals are intoxicated.

OBJECTIVES

To date, however, no research has looked at how best to interview such witnesses to maximise the amount of accurate information they recall.

METHODS

In the present research, whilst on a night out, participants watched a videoed theft whilst either sober or moderately (MBAC = 0.05%) or severely (MBAC = 0.14%) intoxicated. A week later, in a different location, participants were interviewed using either the Enhanced Cognitive (ECI) or Structured Interview.

RESULTS

The ECI was found to improve the recall accuracy and completeness of witness accounts across all three drinking conditions. However, no significant interaction was indicated between alcohol and interview condition.

CONCLUSIONS

The study findings are discussed in terms of their real-world value in aiding police officers to elicit as complete and as accurate an account as possible from intoxicated witnesses.

An experimental examination of the effects of alcohol consumption and exposure to misleading postevent information on remembering a hypothetical rape scenario

We experimentally examined the effects of alcohol consumption and exposure to misleading postevent information on memory for a hypothetical interactive rape scenario. We used a 2 beverage (alcohol vs. tonic water) × 2 expectancy (told alcohol vs. told tonic) factorial design. Participants (N = 80) were randomly assigned to conditions. They consumed alcohol (mean blood alcohol content = 0.06%) or tonic water before engaging in the scenario. Alcohol expectancy was controlled by telling participants they were consuming alcohol or tonic water alone, irrespective of the actual beverage they were consuming. Approximately a week later, participants were exposed to a misleading postevent narrative and then recalled the scenario and took a recognition test. Participants who were told that they had consumed alcohol rather than tonic reported fewer correct details, but they were no more likely to report incorrect or misleading information. The confidence-accuracy relationship for control and misled items was similar across groups, and there was some evidence that metacognitive discrimination was better for participants who were told that they had consumed alcohol compared with those told they had tonic water. Implications for interviewing rape victims are discussed.

The impact of own and others' alcohol consumption on social contagion following a collaborative memory task

When one person alters his or her recollection of an event to be consistent with another person's erroneous account of the same event, social contagion has occurred. In two studies, we examined whether alcohol consumption influences the degree to which people engage in social contagion. In Study 1, participants consumed alcohol, an alcohol placebo, or a soft drink and then completed a collaborative recall test with a confederate who consumed a soft drink. In Study 2, participants consumed a soft drink and then completed a collaborative recall test with a confederate they believed had consumed a soft drink or alcohol (but no alcohol was ever consumed). In both studies, the confederate made scripted errors during the collaborative recall test. On post-collaborative individual recall and recognition tests, participants in both studies engaged in social contagion by including the confederate's errors in their own recollection. In Study 1, the drink participants consumed had no influence on social contagion. In Study 2, participants were less likely to engage in social contagion after collaborating with a confederate who had seemingly consumed alcohol. That same confederate was viewed as less accurate, trustworthy, and credible, which likely made participants less inclined to engage in social contagion.