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Role of Confirmation Bias in Suspect Interviews: A Systematic Evaluation

NCJ Number
Legal and Criminological Psychology Volume: 13 Issue: Part 2 Dated: September 2008 Pages: 357-371
Carole Hill; Amina Memon; Peter McGeorge
Date Published
September 2008
This study examined relationships between presumptions of guilt and interviewing styles.
The results indicate that expectations of guilt would indeed have an effect on questioning style and that this in-turn would lead to a self-fulfilling prophecy effect. There were three studies presented in this paper which systematically examined the effect of expectations of guilt on interviewer questioning style, confession, denial rates, and suspects' verbal behavior during an interview. In the first study, expectations of guilt resulted in the formulation of more guilt-presumptive questions even when participants were free to generate their own questions. In the second study, a significant association was found between suspect guilt/innocence and whether they confessed or denied, although there was no association between questioning style and confession or denial rates. However, in the third study, ratings of independent observers who listened to tape recordings of the suspect interviews indicated an influence of questioning style on the suspects' verbal behavior, whereby a self-fulfilling prophecy effect occurred. Data were derived from undergraduate students at a university in the United Kingdom who were recruited to participate in the three studies. In Study 1, 61 participants formulated questions that they wanted to ask a suspect to determine whether or not they cheated on a task. Prior to formulating their questions, participants were led to believe that the suspect was likely to be guilty or innocent. In Study 2, 45 innocent and guilty participants were interviewed with either guilt-presumptive questions or neutral questions. In the final study, 58 participants listened to a selection of audio taped interviews from Study 2. They then rated various aspects of the suspects' verbal behavior. Table and references