Investigative Utility of the Cognitive Interview: Describing and Finding Perpetrators

The Cognitive Interview (CI) has been shown repeatedly to enhance witness recall of events. The current study examined two conspicuous holes in the CI literature: (a) whether the CI improves witness descriptions specifically of a perpetrator's appearance; and (b) whether CI-elicited perpetrator descriptions help investigators to find the perpetrator. We examined these issues across three studies: In Experiment 1, 67 college students witnessed a simulated robbery and were then interviewed using either the CI or a standard police interview (SI) to elicit a description of the robber. The CI elicited almost three times as many descriptors, and at comparable levels of accuracy. These descriptions were then given to 387 college students (Experiment 2 and 3) and to 71 police officers (Experiment 3), who attempted to find the perpetrator (among a group of suspect photographs). The CI-elicited descriptors increased the rate of finding the perpetrator by almost 30% for both student and police investigators, who did not differ from one another. This study is the first to find that the CI can be properly used by police in a criminal investigation. Investigating the actual perpetrator as opposed to an innocent suspect is likely to have implications for subsequent phases of an investigation, such as increasing the base rate of including perpetrators in lineups. Public Significance Statement The Cognitive Interview allowed witnesses to provide more thorough descriptions of perpetrators than a typical police interview protocol. Use of the Cognitive Interview allowed police investigators to identify perpetrators more efficiently (not wasting time pursuing innocent suspects), and is likely to have a domino effect on subsequent phases of the investigation, including increasing the likelihood of including perpetrators in lineups.