Reducing tunnel vision with a pen‐and‐paper tool for the weighting of criminal evidence

Abstract

In order to prevent tunnel vision, and ultimately miscarriages of justice, police, prosecutors, and judges must remain open to alternative scenarios in which the suspect is in fact innocent. However, it is not evident from the literature that people are sufficiently aware of how alternative scenarios should be employed in the decision‐making process. In the present research, participants read a case vignette and formed an impression of the suspect's guilt. Some participants were made familiar with an alternative scenario. Others were not only presented with an alternative scenario but were also instructed to score (with pen and paper) the extent to which every piece of evidence fitted in the primary and the alternative scenario. Findings suggest that this pen‐and‐paper task helped to reduce tunnel vision.

Test of the analysis of competing hypotheses in legal decision‐making

“…Participants were asked to rate police findings and to decide whether or not to convict the main suspect. Rassin (2018) found that the pen‐and‐paper tool counteracted an excessive focus on evidence confirming the main hypothesis in both lay people and criminal justice professionals. The pen‐and‐paper tool group also had a lower conviction rate than the alternative scenario group.…”

“…Ask & Granhag, 2005; Marksteiner, Ask, Reinhard, & Granhag, 2011; O'Brien, 2009). Rassin (2018) also found that participants showed tunnel vision in response to an incriminating case file. The findings of the current study are thus not in line with previous research, as the initial impression of guilt did not cause a preference for incriminating information.…”

“…However, the more explicit suggestion of an alternative scenario in the current study, which clearly implicated an alternative perpetrator, may have countered confirmation bias more than the exonerating information included in previous studies. Although Rassin (2018) similarly included an explicit alternative perpetrator, based on the material used by Ask and Granhag (2005), he did not find students to be less influenced by the hypothesis of the main suspect than students who did not receive information about an alternative suspect. A possible explanation for that differing finding, thought to be due to the sample of participants, is described below.…”

“…The consideration of alternative scenarios in legal decision‐making has also been investigated by Rassin (2018). In his study, some participants were presented with an alternative scenario in a criminal case whereas others were additionally instructed to indicate how well each piece of evidence fitted with the main and the alternative hypothesis, respectively.…”

The influence of guilt presumptive language on investigative interview outcomes

“…Thus, the motivation to be accurate in the guilty scenario increases, which also increases the likelihood of seeking information that confirms the presumption . Recent research has suggested that weighting criminal evidence using pencil and paper to make notes, whilst considering alternative scenarios, helps to reduce confirmation bias in criminal investigation contexts (see Rassin, 2018). Further examination of such a tool is warranted for the police-suspect interview and could be employed in the planning and preparation phases present in both the PEACE and the GIS framework.…”