No abstract

Expectancy effects are known to influence behaviour so that what is expected appears to be true. In this study, expectancy was induced using (fabricated) information about honesty and specific group membership. Targets were tested in a non-accusatory interview environment using neutral and information-gathering questions. It was hypothesized that those exposed to the negative information (the expectancy) would demonstrate behaviour consistent with an increased cognitive load, and evidence was found to support this prediction. Due to the investigative nature of the information-gathering questions, it was also expected that the targets exposed to the expectancy would exhibit more of these behaviours in the investigative portion of the interview. Some behaviour was found to support this prediction (i.e. shorter responses and increased speech disturbances); however, indicators of performance altering load were not observed during this phase of the interview. These findings support the hypothesis that expectancy effects can noticeably alter interviewee behaviour.

The aim of the current study was to obtain a snapshot of police officer's beliefs about factors that may influence the outcome of the investigative interview with suspects. We created a 26-item survey that contained statements around three specific themes: best interview practices, confessions and interviewee vulnerabilities. Police officers (N = 101) reported their beliefs on each topic by indicating the level of agreement or disagreement with each statement. The findings indicated that this sample of officers held beliefs that were mostly consistent with the literature. However, many officers also responded in the mid-range (neither agree nor disagree) which may indicate they are open to developing literature-consistent beliefs of the topics. Understanding what officers believe about factors within the investigative interview may have implications for future training. It may also help explain why some officers do not consistently apply best practices (i.e. strong counterfactual beliefs) versus officers who reliably apply literature-consistent practices to their interviews (i.e. knowledge-consistent beliefs).