This article presents an expected cost model for evaluating and comparing the performance of eyewitness identification procedures. The model estimates the expected cost of an identification procedure in order to quantify how well the procedure helps the police achieve the investigation goal of identifying and incriminating the culprit. We first apply the expected cost model to analyze five major procedural reforms, including showups versus lineups, filler similarity, administrator influence, lineup instruction, and presentation format. Our analysis reveals that when there is a trade-off between accurate and mistaken identifications, conclusions about procedural superiority depend on the prior probability of guilt and relative costs of different identification outcomes. We then conduct an additional analysis based on a simultaneous consideration of all identification outcomes (i.e., suspect identifications, filler identifications, and rejections). Our analysis shows that assuming different costs for filler identifications and rejections can change conclusions about procedural superiority. We conclude by discussing insights provided by the expected cost model regarding how the legal system can reduce expected costs of eyewitness identification-by changing the conditional probabilities, by reducing the costs of identification outcomes, or by increasing the prior probability of guilt. Public Significance StatementThe expected cost model considers the probability that a suspect is the culprit before an identification occurs, the probabilities of eyewitness responses, and the costs of eyewitness responses. The model ultimately estimates the ability of an eyewitness identification procedure to help police achieve the investigation goal of identifying and incriminating culprits. It provides a useful tool for researchers and policymakers to evaluate eyewitness identification procedures.

This article proposes an effect taxonomy to organize and categorize the interrogation techniques that police often use to elicit confessions from suspects during custodial interrogations. The effect taxonomy categorizes techniques into one of four categories according to how interrogation techniques differently influence guilty and innocent suspects: confession-prone, differentiating, assimilating, and nonconfession-prone. To apply the effect taxonomy, we employ the interrogation decision-making model (Yang, Guyll, & Madon, 2017) to analyze the 16 interrogation techniques used in Kassin and colleagues' ( 2007) national survey on police interrogation practices. Our analysis revealed that the majority of the interrogation techniques are confession-prone, thus increasing the likelihood of confessing for both guilty and innocent suspects. Our analysis also revealed several differentiating techniques, which increase the likelihood of confessing only for guilty suspects but not for innocent suspects. In addition, we also identified the interrogation duration as a potentially differentiating factor for guilty and innocent suspects, such that limiting the length of an interrogation will protect innocent suspects from falsely confessing. The findings from the effect taxonomy have important implications for the legal system: Police should be aware of the effects of the interrogation techniques to avoid using confession-prone interrogation techniques and employ differentiating techniques that increase the likelihood of confessing for guilty suspects but not innocent suspects.

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