Just a few words: the influence of positive and negative bias on participants' judgements of an interviewee's mental health

We report a practical exercise in abnormal psychology designed to give students an insight into social stereotypes. Apart from bringing to life, through the student's personal experience, important issues in psychiatric diagnosis, the study enables an entré to accessible published studies in the related literature, consideration of the ethics of deception, comparison of questionnaire and qualitative interview data, and discussion of experimental design, statistical testing and basic elements of psychometrics. Ninety-six newly arrived undergraduates viewed a 25-minute video of a female nurse. In a 2X2 factorial design the alleged nature of the interview was varied (job interview or psychological assessment) as was the rating scale information (exposure prior to the video, after the video). Students then rated the mental status of the interviewee on 20 items and reflected in small discussion groups on what they had seen. Ten items showed significant experimental effects, four as a result of prior information about the nature of the interview, five as a result of prior exposure of the questionnaire, and there was one interaction between treatments. Participants saw the person as less healthy when the interview was said to be psychological assessment, and more healthy having seen the questionnaire prior to the video. Qualitative data from the small group discussions reflect the quantitative experimental data, the same interview generating contradictory views of the interviewee. Apart from its pedagogical benefits the study replicates previous studies supporting labelling theory and negative bias but also shows unlike the previous literature that prior exposure induces a positive bias. Students wrote up the practical exercise and discussed its various implications with personal tutors.