Deception Detection and Suspect´s Counter-Interrogation Strategies

Abstract: Degree of Licentiate in Psychology Abstract Clemens, F. (2010). Deception Detection and Suspects' Counter-Interrogation Strategies. Department of Psychology, University of Gothenburg, Sweden In legal settings correct discriminations between truthful and deceptive statements are of major importance. However, deception detection research shows that lay people, as well as presumed lie experts working within the legal field, rarely achieve accuracy rates above the level of chance. One reason for the low accuracy rates typically found is that differences in behaviour between truth tellers and liars are very subtle, and that there are very few reliable cues to deception. Trying to actively elicit cues to deception (via the Strategic Use of Evidence (SUB) technique) is a new approach that aims at making differences between truth tellers and liars more salient. In the current thesis the SUE-technique is tested for the first time on children acting as mock-suspects (Study 1). In addition, adult suspects' counterinterrogation strategies are investigated (Study 2). Stndy 1 consisted of two experiments. Experiment l focused on the elicitation of diagnostic cues to deception using two types of evidence disclosure techniques (i.e., late evidence disclosure (SUB-technique) vs. early evidence disclosure) when interviewing children (N = 84) who were either guilty or innocent of a mock crime. The results showed that deceptive children omitted significantly more crime-related information than truth-telling children. Furthermore, deceptive children's statements were significantly more inconsistent with the evidence than were the truth-telling children' s statements and this was more pronounced as a function of late compared to early disclosure of evidence. Experiment 2 exarnined to what extent the elicited cues helped receivers (N = 168) to assess the veracity of the children' s statements. The results showed an overall accuracy level of 59.5%, which was significantly above the level of chance. The observers in the late disclosure condition performed better than chance whereas the observers in the early condition did not. However, the difference between these two conditions in terms of accuracy was non-significant. Study 2 investigated guilty mock-suspects' (N = 90) counter-interrogation tactics with respect to the disclosure of possibly self-incriminating information. Specifically, the extent to which the disclosure of this information was moderated by (a) the suspects' criminal experience (nåive vs. experienced), and (b) the degree of suspicion directed towards the suspects (low vs. high). The results showed that experienced (vs. naive) suspects volunteered less self-incriminating information in an initial free recall phase. When asked crime-specific questions, experienced (vs. nåive) suspects admitted having committed less actions fitting with the crime under investigation. Furthermore, experienced suspects' willingness to report information was not affected by the degree of suspicion, whereas nåive suspects in the high-suspicion (vs. low-suspicion) condition were more willing to report information. This thesis presents research that deals with the active elicitation of diagnostic cues to deception by interrogating strategically with respect to the information at hand (Study l), and it exarnines suspects' counter-interrogation strategies (Study 2). Combining these two approaches is important in order to make deception detection assessments more reliable. Keywords: deception detection, interview techniques, strategic use of evidence, counterinterrogation tactics, degree of suspicion, criminal experience, guiIty suspects Franziska Clemens, Department of Psychology, University of Gothenburg, P.O. Box 500, 40530 Gothenburg, Sweden. Phone:+46317861672, E-mail: [email protected] ISSN 1101-718X ISRN GUIPSYKlA VH--226--SE