Mock‐suspects' decisions to confess: the accuracy of eyewitness evidence is critical

Abstract

Forty participants were asked to commit a mock-crime that involved them stealing a cell-phone. Later the mock-offenders were questioned and evidence was presented to them from a witness who was said to have seen the offence. Participants were randomly assigned to one of two conditions in which they were presented with a witness statement that either contained detailed information concerning their description and their actions, or not-detailed information. For half the participants in each condition the information was correct, while for the other half some of the information was incorrect. The results show that participants were more likely to confess if the evidence against them was accurate, but the level of detail of the evidence made no difference. Participants who had accurate evidence presented against them felt more guilty than those who had less accurate evidence against them. The results are discussed in relation to police interviewing techniques.

Interviewing suspects: examining the association between skills, questioning, evidence disclosure, and interview outcomes

“…For example, several studies have found an association between the revelation of evidence and the gaining of further information (Bull & Leahy-Harland, 2012;Nystedt, Nielsen, & Kleffner, 2011;van der Sleen, 2009), while other (experimental) studies have revealed that certain evidence disclosure strategies have contributed to the rigorous testing of given accounts by mock suspects, and, in turn, the detection of either lies or truth (Dando, Bull, Ormerod, & Sandham, in press;Granhag, Strömwall, Willén, & Hartwig 2012;Hartwig, Granhag, Strömwall, & Kronkvist 2006;Hartwig, Granhag, Strömwall, & Vrij, 2005;Sorochinski et al, 2014). Yet other studies have found that disclosing strong evidence is associated with suspects' confessions (Bull & Soukara, 2010;Cassell & Hayman, 1996;Gudjonsson & Petursson, 1991;Kebbell, Hurren, & Roberts, 2006;Moston, Stephenson, & Williamson, 1992;Sellers & Kebbell, 2009;Soukara et al, 2009;Walsh & Bull, 2012a). These studies have provided consistency when concluding how important evidence disclosure is; however, there is much less agreement between them as to what particular strategy is more effective than another.…”

When should evidence be disclosed in an interview with a suspect? An experiment with mock‐suspects

“…Participants were then asked to rate, on a ten-point Likert scale, their likelihood of confessing to the crime. The fourth step was taken from Kebbell et al (2006); participants were promised $10 which they could keep if they successfully fooled a mock-jury into believing they were innocent, and were offered $5 if they confessed to the theft, but those who made a denial which was not believed were given no money. Participants were then asked 'Do you confess or deny stealing the phone?'…”

“…Whilst some participants were given innocent instructions, the data from these individuals were not analysed. Participants were instructed to go into a room and steal a mobile phone, and were observed whilst they did this (for more details on the methodology see Kebbell et al, 2006).…”

Sex offenders’ perceptions of the effectiveness and fairness of humanity, dominance, and displaying an understanding of cognitive distortions in police interviews: A vignette study

“…A major impediment for research in suspect interviewing involves the potential influence of confounding variables. Field studies and offenders' self-report surveys into suspect interviewing are always likely to be hampered by the possibility of confounding variables, particularly the variation in evidence, which, exerts a very powerful impact on the decision to confess (see Gudjonsson & Petursson, 1991;Gudjonsson & Sigurdsson, 1999;Kebbell, Hurren, & Roberts, 2006;Moston, Stephenson, & Williamson, 1992). For instance, one cannot firmly conclude that there is a direct causal relationship between humanity and confessions, and between dominance and denials from Holmberg and Christianson's (2002) paper because variations in strength of evidence represents a third, and critical confounding variable.…”