‘The intoxicated co-witness: How alcohol and discussion affect eyewitness memory reports.

Intoxicated witnesses are routinely encountered by law enforcement officers (Evans, Schreiber Compo & Russano, 2009). Such witnesses may have discussed details of the crime with each other prior to having their statement taken (Skagerberg & Wright, 2008). In order to understand the consequences of co-witness discussion on intoxicated witnesses, three studies were conducted investigating the effect of intoxication on misinformation when (a) the source of misinformation is a written statement from a seemingly intoxicated source in an online study; (b) when two intoxicated dyad partners engage in a face to face discussion in a laboratory based, alcohol administration study; and (c) when an intoxicated person encounters post event information from a sober video witness in the field.
The results suggest that intoxication does not influence the tendency to report misinformation. This is consistent when the source of misinformation is perceived to be intoxicated and the recipient is sober, both co-witnesses are intoxicated, or the recipient of misinformation is intoxicated whilst the source is sober. Intoxication also does not influence source monitoring ability. That is, both sober and intoxicated participants are equally able to identify the source of their memory recall. The results also add to the current literature on the effect of intoxication on eyewitness memory at an individual level. They demonstrate that at moderate doses, whilst accuracy is not impaired, intoxication may reduce the completeness of recall and the confidence a witness has in their memory. At higher doses however, in addition to the detrimental effects of alcohol on confidence and completeness, accuracy is also impaired.
The findings have implications for the criminal justice system given that intoxicated witnesses usually complete their evidential interview at a later date when sober (Crossland, Kneller & Wilcock, 2018). Witnesses who were intoxicated at the time of the crime and who engaged in co-witness discussion are no more prone than their sober counterparts to report co-witness information and are equally able to identify the source of the information that they report. Additionally, an intoxicated witness may report fewer details, and the accuracy of their statement may be influenced by their degree of intoxication. As such, breathalysing witnesses at the scene of the crime should be encouraged in order to understand the likely effect intoxication will have on their testimony.