Changing the Game: Influencing Suspects to Disclose Information in Investigative Interviews with the Shift-of-Strategy Approach

Abstract

The Shift-of-Strategy (SoS) approach is a recently conceptualized interviewing technique aimed at encouraging suspects to disclose information during investigative interviews. Prior to this thesis, the approach had demonstrated its efficacy in one laboratory test, making further testing vital to build confidence in the approach. The overarching aim of this thesis was to advance the research on the approach by assessing its performance across a series of laboratory tests. Our primary measure of interest concerned the amount of truthful and crime-relevant information participants disclosed during mock interviews. Specifically, we separately assessed disclosures that concerned details that were already known by the interviewer, as well as disclosures that revealed completely new information. Study I reassessed the effectiveness of the SoS approach using a more complex mock crime procedure than previously tested. The study also introduced a new variation of the approach (SoS-Reinforcement) which was designed to enhance the core strategies of the SoS approach. Participants (N = 300) were interviewed with one of three techniques: Direct, SoS-Standard, and SoS-Reinforcement. Participants interviewed with SoS-Standard and SoS-Reinforcement disclosed more information than participants interviewed with the Direct approach. However, no meaningful differences were observed regarding disclosures between SoS-Standard and SoS-Reinforcement. Overall, the results provided support for the SoS approach’s ability to obtain new information from suspects in longer and more complex interviews. Study II comprised three sub-studies. Study IIa (N = 159) explored new variations of the approach designed to maintain participants’ engagement and motivation to appear innocent during interviews. Study IIb (N = 60) assessed the approach’s efficacy in a repeated-interview context. Study IIc (N = 75) compared the behavior of innocent and guilty participants when interviewed with the SoS approach. The results from these studies demonstrate the robustness of the SoS questioning procedure while also identifying important boundary conditions, highlighting contexts when the approach is less effective and where its use may be inappropriate. Study III evaluated whether the SoS approach could be effectively taught to novice interviewers and whether SoS training improved interviewers’ ability to obtain information from mock suspects beyond receiving training in fundamental interviewing skills and principles (Basic training). Participants (N = 31) either received the Basic training alone or both the Basic and SoS training, and each participant conducted four interviews with mock suspects (N = 125). Interviews conducted following SoS training used more SoS tactics and obtained more known information from mock suspects than interviews based solely on Basic training. Although we observed no significant differences regarding new disclosures based on training, exploratory analyses revealed that the use of SoS tactics was positively associated with obtaining both known and previously unknown information. In conclusion, this thesis provides strong evidence for the SoS approach as an effective method for obtaining new information from suspects, while also clarifying the conditions that support or limit its success.