Determinants of Guilty Suspects’ Behavior in Investigative Interviews: Evidence-Disclosure Tactics and Question Content

Abstract: Research in the Strategic Use of Evidence (SUE) paradigm has shown that guilty suspect’s verbal behavior is a product of the counter-interrogation strategies suspects employ based on the prior knowledge they believe interviewers hold about their crime-related activities. This thesis proposes a broader understanding of these constructs that influence guilty suspects’ behavior. Study I-a (N= 140) tested four SUE-based interviewing tactics to influence counter-interrogation strategies and elicit statement-evidence inconsistencies. A mock crime paradigm was used consisting of three activities as part of a single crime carried out by mock-suspects. Evidence-disclosure tactics were manipulated as Early Disclosure (early in the interview), Strategic Disclosure (late disclosure based on suspect’s statement), Non-Disclosure (evidence was not disclosed throughout the interview) and Direct Questioning (a question only about the critical aspect of the crime asked without evidence disclosure). No differences were found between the conditions in the predicted direction. On further analysis, it was found that suspects used forthcoming strategies and stayed close to the truth about non-critical (less incriminating) activities of the crime but used avoidance or denial strategies regarding the critical aspect (highly incriminating) of the crime irrespective of the interview condition. As a follow-up, Study I-b (N=216) was designed to test if this finding would be replicated. The mock crime with four activities was manipulated so that it consisted of two less critical (non-incriminating) activities and two very critical (highly incriminating) activities. Three interview conditions from study I-a were used, namely: Early Disclosure, Strategic Disclosure and Non-Disclosure. As predicted, it was found that suspects stayed close to the truth with non-incriminating activities of the crime but used avoidant and denial strategies regarding the incriminating activities. In Study II (N=370) question content factors influencing guilty suspects’ Perceived Interviewer Knowledge (PIK) were tested. Three factors were tested: Topic Discussion (whether a specific crime-related activity was discussed in the interview), Level of Specificity (the amount and type of crime-related details within questions), and Stressor (emphasis on crime-related details in the questions). Based on psycholinguistic theories, it was predicted that Topic Discussion and higher amount of specific correct crime related details would increase PIK. Additionally, it was predicted that incorrect details and stressors would reduce PIK. However, there was only support for predictions regarding Topic Discussion. Finally, Study III (N=232) was developed based on the theory and findings of Study II. Topic Discussion, Level of Specificity (modified from Study II) and a new factor- Level of Suspicion were tested. It was predicted and found that Topic Discussion increased PIK as observed in Study II. It was also predicted that high Level of Suspicion in questions would increase PIK, but there was no support for this prediction. However, there was partial support for the predictions regarding Level of Specificity in that, high specificity questions induced higher PIK when the topic was discussed. Overall, the findings shed light on the complex nature of guilty suspects’ cognitive processes also provide a nuanced understanding of the perceived interviewer knowledge construct that is critical to the behavioral outcome of suspects.