Tunnel Vision and Confirmation Bias Among Police Investigators and Laypeople in Hypothetical Criminal Contexts

Tunnel vision is the tendency of actors in the criminal justice system to use short-cuts to filter evidence selectively to build a case for a suspect’s conviction. Confirmation bias tends to favor information that confirms an individual’s preconceptions independently of the information’s accuracy: the present study manipulated tunnel vision and confirmation bias. The purpose was to examine the combined effects of these biases on Israeli police investigators and laypeople in hypothetical criminal investigation situations. Results indicated that police investigators were more strongly affected than laypersons by tunnel vision. Police investigators were more confident about the suspect’s guilt than were laypeople in the presence of incriminating and exonerating information, alike. Still, investigators did not ignore exonerating information and lowered their confidence in the suspect’s guilt when exonerating information was presented. We discussed the results according to police legitimacy and self-assessed lie-detection ability, which is rated higher by police investigators than by laypeople.