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.