A meta‐analysis of the effects of acute alcohol intoxication on witness recall

Abstract

There is widespread belief in the legal system that alcohol impairs witness testimony.Nevertheless, most laboratory studies examining the effects of alcohol on witness testimony suggest that alcohol may affect the number of correct but not incorrect details recalled. However, it is difficult to draw conclusions because sample sizes, testing paradigms, and recall measures vary between individual studies. We conducted a metaanalysis to address this issue. We found alcohol intoxication had a significant and moderate sized effect on the number of correct details recalled (g = 0.40). The effect of alcohol on the number of incorrect details recalled was not significant. Further, the effect of alcohol on the recall of correct details was significantly moderated by multiple factors like intoxication level, the retention interval length between encoding and recall, and the types of questions asked (i.e., free recall vs. cued recall). We discuss the applied implications of the results.

The influence of alcohol and weapon presence on eyewitness memory and confidence

“…It is difficult to evaluate the present alcohol and scene memory data in the context of the contrasting methods and findings of earlier work (for reviews see Altman et al, 2019;Jores et al, 2019) but our results are at least consistent with several studies reporting null F I G U R E 6 Calibration curves for each alcohol group as a function of weapon absence and weapon presence alcohol effects (e.g., Crossland et al, 2016, Experiment 1;Hagsand et al, 2017;Harvey et al, 2013b;Hildebrand Karlén et al, 2017;Schreiber Compo et al, 2012). We note, however, that the absence of a "don't know" response option on our questionnaire likely inflated guessing rates, which may vary as a function of alcohol level.…”

“…Schreiber Compo (2019) had placebo, low dose (BAC = 0.04%), and high dose (M BAC = 0.11%) alcohol groups watch a film clip depicting a highly traumatic sexual assault and found the highest alcohol dose impaired peripheral recall (memory of the staged screening room and its contents) but had no effect on central recall (memory of the film clip itself). We note that the Jaffe et al's experiment was published after a meta-analysis of acute alcohol and scene memory effects by Jores et al (2019), who report evidence of peripheral but not central alcohol deficits across several studies.…”

“…In a similar study conducted across seven English police forces, 82% of officers claimed intoxicated witnesses were either a common or a very common occurrence (Crossland, Kneller, & Wilcock, ). However, conclusions from applied forensic memory research are mixed as variations in alcohol dose, retention period, encoding–retrieval intoxication state, and type of test exert a complex influence on witness performance (for reviews see Altman, Schreiber Compo, Hagsand, & Evans, ; Jores, Colloff, Kloft, Smailes, & Flowe, ).…”

“…Those most intoxicated while viewing the clip (M BAC = 0.14%) recalled fewer correct details of it than viewers with lower breath readings (M BAC = 0.05%), but recognition memory performance was unaffected by alcohol. Furthermore, following a meta‐analysis of the alcohol and scene recall literature, Jores et al () found only small adverse effects of low to moderate alcohol doses on the completeness of recall, but larger impairments to both recall completeness and accuracy at higher doses (BAC ≥ 0.10%). This perhaps explains why null effects of alcohol on scene memory are commonly reported in lab studies which, for ethical reasons, rarely elicit BACs above 0.10% (e.g., Hagsand et al, ; Harvey, Kneller, & Campbell, ; Hildebrand Karlén, Roos af Hjelmsäter, Fahlke, Granhag, & Söderpalm‐Gordh, ; Schreiber Compo et al, ).…”

“…Evidence that alcohol restricts attention to the processing of salient visual features is provided by a raft of basic cognitive experiments (e.g., Bayless & Harvey, ; Canto‐Pereira, David, Machado‐Pinheiro, & Ranvaud, ; Clifasefi, Takarangi, & Bergman, ; Harvey, ; Harvey, Bayless, & Hyams, ; Hoyer, Semenec, & Buchler, ; Moskowitz & Sharma, ; Schulte, Müller‐Oehring, Strasburger, Warzel, & Sabel, ) and a small but growing number of applied studies on alcohol and mock‐witness recall (for reviews see Altman et al, ; Jores et al, ). For example, Harvey et al () tracked the eye movements of sober and alcohol (M BAC = 0.06%) participants as they viewed two successive stimulus photographs each depicting a salient real‐world scene as its focus (e.g., riot police apprehending civilians with batons).…”