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.

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This reviews the literature in psychology on acute alcohol intoxication and memory. Special emphasis is placed on empirical studies that have systematically examined alcohol's effects on memory performance in forensic contexts. Three aspects of memory performance are considered, including memory accuracy (i.e., the ability of the complainant to accurately distinguish between correct and incorrect information about the crime), memory reliability (i.e., the probability that information recalled by the complainant at a given level of certainty is correct), and completeness (i.e., the quantity of information reported by the complainant). The results show that different memory performance measures are differentially important depending on whether we are policy makers formulating interview guidance, versus decision makers evaluating the strength of memory evidence in a given case. Overall, the research to date indicates that acute alcohol intoxication during rape affects the completeness but not the accuracy of what is remembered.

Children are frequently victims and witnesses of crime. In the witness identification literature, children are deemed to have unreliable memories. Yet, in developmental research, even young children display appropriate metacognitive cues that reflect their accuracy. To address these contradictory findings, we asked children in young- (4–6 years), middle- (7–9 years), and late- (10–17 years) childhood (N = 2,205) to watch a person in a video, and then identify that person from a police lineup. We asked children to provide a confidence rating for their identification decision (a direct metacognitive cue), and used an interactive lineup—in which the lineup faces can be rotated and viewed from different angles—to analyze children’s viewing behavior (an indirect metacognitive cue). According to calibration statistics that have traditionally been calculated in the witness literature, confidence was only informative about accuracy in late-childhood. Confidence-Accuracy Characteristic analysis, however, suggested that confidence and accuracy were related and high-confidence suspect identifications were highly accurate in middle- and late- childhood. Moreover, in all age groups, viewing behavior on the interactive lineup differed in children who made correct compared to incorrect suspect identifications. Our research suggests that the fundamental architecture of metacognition that has previously been evidenced in the developmental literature on relatively simple tasks, also underlies performance on complex tasks like an identification from a lineup. Moreover, our findings are practically important for legal professionals interpreting child memory evidence: Namely, identifications made by children can be reliable when appropriate metacognitive cues are used to assess accuracy.