University of Twente Student Theses


Impact of Interviewer Assumptions on the Outcomes of Investigative Interviews

Hudepohl, B.A.E. (2023) Impact of Interviewer Assumptions on the Outcomes of Investigative Interviews.

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Abstract:Police services rely heavily on information collected through interviewing suspects. Interviewer perceptions are found to not always be as objective as they should be. Factors which were found to influence those perceptions are guilt presumptions, which influence investigative decisions that are made. This could cause miscarriages of justice or could lead to false convictions. The purpose of this study is to show the influence of guilt presumptions on guilt judgements, the intention to further investigate the suspect, the perceived plausibility of the suspect’s story, the purpose of an investigative interview and the confidence in one’s own ability to determine guilt. Furthermore, the differences in these variables between experts (police officers) and non-experts (lay people) will also be investigated. The experimental design was a between-subjects design with the independent variables guilt presumptions (guilt presumption versus innocence presumption) and experts (experts versus non-experts). The design required participants to conduct a face-to-face interview with a suspect, together with filling in a pre- and post-questionnaire. The sample consisted of 35 participants (non-experts) and 16 police officers (experts). The manipulation of the guilt presumption was not as strong as hoped, especially in manipulating innocence beliefs. However, it is of importance to highlight the finding that two third of the participants in the non-expert group assumed guilt, while almost no participant in the expert group assumed guilt when the interview was finished. Another interesting finding was that the variable of the perceived plausibility of the suspect’s story had a significant negative correlation with the pre- and post-interview measures on guilt judgement. This indicates that participants who believed the suspect was guilty perceived the story the suspect told as less plausible, even though they were given a plausible explanation by the suspect. Perceived plausibility of the suspect’s story was also correlated with the variable of confidence and the intention to further investigate. Future research should focus on enlarging the sample size of the experts as well as non-experts, so the results can be considered as more reliable. Also, involving police detectives in setting up the experiment, and with that in writing and formatting the interview script, would increase the ecological validity.
Item Type:Essay (Bachelor)
Police Academy, Apeldoorn, The Netherlands
Faculty:BMS: Behavioural, Management and Social Sciences
Subject:77 psychology
Programme:Psychology BSc (56604)
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