Witnesses’ memory for events and faces under elevated levels of intoxication

The influence of acute alcohol intoxication and hair visibility on delayed face recall

Many witnesses are intoxicated at crime scenes, yet little is known of their ability to accurately describe perpetrators to police. We therefore explored the impact of alcohol on delayed verbal face recall across two experiments. Participants were administered an alcoholic or non-alcoholic beverage prior to viewing either one or two unfamiliar female faces, which they described from memory the following day while in a sober state. Each to-be-remembered model had long hair worn either loose (i.e., visible), or tied behind the head (i.e., concealed). Testing the hypothesis that alcohol narrows the focus of attention to the external (hairstyle) region of faces, we expected intoxicated participants to have poorer memory of internal face features (eyes, nose, mouth) than sober controls for stimulus faces with visibly long hair. Results revealed poorer recall accuracy for internal face details following alcohol consumption (Exp. 2), but the effect was uninfluenced by hairstyle. Findings are therefore consistent with the more general view that alcohol is associated with a bias to the external (hairstyle) region of faces during face learning, irrespective of hair visibility.

Alcohol Use Predicts Face Perception Impairments and Difficulties in Face Recognition

Background: Risky alcohol use is related to a variety of cognitive impairments, including memory and visuo-perceptual difficulties. Remarkably, no prior work has assessed whether usage of alcohol can predict difficulties perceiving facial identity. Objectives: Therefore, this study aimed to investigate whether riskier alcohol consumption predicted impairments in face perception and self-reported difficulties in face recognition. Results: Participants (N = 239, male = 77) were over 18 years old and had normal or corrected-to-normal vision. Alcohol use was assessed using the Alcohol Use Disorder Identification Test (AUDIT), while face recognition difficulties were determined by the 20-item Prosopagnosia Index questionnaire (PI20). A subsample of participants (N = 126, male = 51) completed the Cambridge Face Perception task (CFPT) to assess their face perception ability. Multiple linear regressions showed significant models of prediction on both face perception and face recognition when considering AUDIT score and age as predictors. Conclusion: This study suggested, for the first time, that risky alcohol use predicts both poorer visuo-perceptual processing for faces and self-reported difficulties in face recognition.

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.

The importance of the smallest effect size of interest in expert witness testimony on alcohol and memory

Memory experts are sometimes asked to evaluate the validity of accounts of witnesses, victims, or suspects. In some of these cases, they are asked what effect alcohol has on the validity of such accounts. In this article, we offer a guide on what expert witnesses can reliably say about how alcohol affects memory. We do so by resorting to effect sizes from previous studies and meta-analytic work, and address this novel question: Are these effect sizes meaningful in legal cases? More specifically, we argue that any determination of whether individual studies about alcohol and memory are practically relevant for legal cases, scientists must focus on the smallest effect size of interest. We make the case that a decrease or increase of only 1 detail, especially an incorrect detail, should be regarded as the smallest effect size of interest in this line of research. In line with this idea, we show that effect sizes in the alcohol and memory literature are often larger than this smallest effect size of interest. This finding is important because it implies that alcohol often exerts a practically relevant and meaningful detrimental effect on the reporting of both correct and incorrect details, which in turn negatively affects the validity of witness testimony.

Would you believe an intoxicated witness? The impact of witness alcohol intoxication status on credibility judgments and suggestibility

Memory conformity may occur when a person’s belief in another’s memory report outweighs their belief in their own. Witnesses might be less likely to believe and therefore take on false information from intoxicated co-witnesses, due to the common belief that alcohol impairs memory performance. This paper presents an online study in which participants (n = 281) watched a video of a mock crime taking place outside a pub that included a witness either visibly consuming wine or a soft drink. Participants then read a statement from the witness that varied in the number of false details it contained before being asked to recall the crime. We found that the intoxicated witness was regarded as significantly less credible, but participants were not less likely to report misinformation from them. This suggests that intoxication status impacts one’s perception of how credible a source is, but not one’s ability to reject false suggestions from this source. Our findings reinforce the importance of minimizing co-witness discussion prior to interview, and not to assume that people automatically (correctly or not) discount information provided by intoxicated co-witnesses.

Police Decision-Making in the Absence of Evidence-Based Guidelines: Assessment of Alcohol-Intoxicated Eyewitnesses

Regarding police procedures with alcohol-intoxicated witnesses, Swedish police officers have previously reported inconsistent and subjective decisions when interviewing these potentially vulnerable witnesses. Most officers have also highlighted the need for national policy guidelines aiding in conducting investigative interviews with intoxicated witnesses. The aims of the two studies presented here were to investigate whether (1) police officers' inconsistent interview decisions are attributable to a lack of research-based knowledge; (2) their decision to interview, as well as their perceptions of the witnesses' credibility could be influenced by scientific research; and (3) police officers decision-making and perceptions of witness credibility are biased by pre-existing social norms. In two separate randomized online experiments, police professionals and recruits (Study 1, N = 43; Study 2, N = 214) watched a recorded fictive witness interview to which they were asked to rate the probability of interviewing the witness, the witness' credibility, and to estimate the witness' level of intoxication. Results showed that interview probability and perceived witness credibility were affected by witness intoxication level. While it cannot be stated definitely from the present research, these findings provided indications that police officers and recruits lacked research-based knowledge. Results also showed that interview probability, but not perceptions of credibility, was influenced by a research-based message. In line with research, interview probability for the most intoxicated witness increased after reading the message. Unexpectedly, neither interview probability nor witness credibility was affected by social norms. The current findings added to the legal psychology literature by showing that a breath alcohol concentration (BrAC) as low as .04% was enough for police officers and recruits to consider intoxicated witnesses less credible than sober witnesses. Findings also indicated that, despite the lower credibility assessment, police may have some understanding that these witnesses can be interviewed at low intoxication levels (i.e., around .04%). However, this willingness to interview intoxicated witnesses ceased at a BrAC lower than the levels where research has found intoxicated witnesses as reliable as sober witnesses (i.e., BrAC < .10%). Future directions for research and policy development as well as theoretical and practical implications of the present findings are discussed.

The effects of alcohol and co-witness information on memory reports: a field study

RATIONALE

Witnesses who discuss a crime together may report details that they did not see themselves but heard about from their co-witness. Co-witness information may have beneficial and harmful effects on memory accuracy depending on whether the information was correct or incorrect.

OBJECTIVES

Given the prevalence of intoxicated witnesses, it is imperative to understand how alcohol influences this effect.

METHODS

The present study asked pubgoers (n = 67) at varying levels of intoxication to recall a mock crime video after having also watched a video witness statement containing both correct and false information.

RESULTS

Increased intoxication was associated with decreased confidence, completeness and accuracy, but no increased tendency to report false information. Exposure to incorrect post-event information (PEI) can lead to the incorporation of incorrect information, whereas exposure to correct PEI increased accuracy, regardless of individuals' alcohol intoxication status.

CONCLUSIONS

Thus, whilst discussion and intoxication can negatively impact eyewitness memory, discussion may also have benefits for both sober and 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.

Alcohol myopia and the distracting effects of hair in face recognition

BACKGROUND

According to alcohol myopia theory, alcohol reduces cognitive resources and restricts the drinker's attention to only the more prominent aspects of a visual scene. As human hairstyles are often salient and serve as important facial recognition cues, we consider whether alcohol restricts attention to this region of faces upon initial viewing.

AIMS

Participants with higher breath alcohol concentrations just prior to encoding a series of unfamiliar faces were expected to be poorer than more sober counterparts at recognising the internal but not external features of those faces at test.

METHODS

Drinkers in a nearby bar (n=76) were breathalysed and then shown a sequence of 21 full face photos. After a filled five-minute retention interval they completed a facial recognition task requiring them to identify the full, internal or external region of each of these among a sequence of 21 previously unseen (part or whole) faces.

RESULTS

As predicted, higher breath concentrations were associated with poorer discrimination of internal but not external face regions.

CONCLUSIONS

Our findings suggest that alcohol restricts unfamiliar face encoding by narrowing the scope of attention to the exterior region of unfamiliar faces. This has important implications for drunk eyewitness accuracy, though further investigation is needed to see if the effect is mediated by gender, hair length and face feature distinctiveness.

Do intoxicated witnesses produce poor facial composite images?

RATIONALE

The effect of alcohol intoxication on witness memory and performance has been the subject of research for some time, however, whether intoxication affects facial composite construction has not been investigated.

OBJECTIVES

Intoxication was predicted to adversely affect facial composite construction.

METHODS

Thirty-two participants were allocated to one of four beverage conditions consisting of factorial combinations of alcohol or placebo at face encoding, and later construction. Participants viewed a video of a target person and constructed a composite of this target the following day. The resulting images were presented as a full face composite, or a part face consisting of either internal or external facial features to a second sample of participants who provided likeness ratings as a measure of facial composite quality.

RESULTS

Intoxication at face encoding had a detrimental impact on the quality of facial composites produced the following day, suggesting that alcohol impaired the encoding of the target faces. The common finding that external compared to internal features are more accurately represented was demonstrated, even following alcohol at encoding. This finding was moderated by alcohol and target face gender such that alcohol at face encoding resulted in reduced likeness of external features for male composite faces only.

CONCLUSIONS

Moderate alcohol intoxication impairs the quality of facial composites, adding to existing literature demonstrating little effect of alcohol on line-up studies. The impact of intoxication on face perception mechanisms, and the apparent narrowing of processing to external face areas such as hair, is discussed in the context of alcohol myopia theory.