Evidence-based suspicion and the prior probability of guilt in police interrogations.

OBJECTIVE: False confessions are prevalent in wrongful convictions, and much research has examined investigation factors and interrogation methods that can contribute to false confessions. However, not all these factors are under the control of the legal system, and improving the effectiveness of interrogation methods has a limited effect on evaluating the veracity of confessions. We suggest incorporating an important but often-neglected factor in interrogations: suspects' prior probability of guilt ("the prior," a Bayesian term meaning suspects' likelihood of being guilty before police conduct an interrogation). METHOD: By connecting interrogation practices to probability concepts, we discuss a gap in the literature between questions traditionally answered by lab research and a distinct question faced by the legal system. RESULTS: On the basis of our analysis, we argue that police should increase priors by collecting additional evidence to satisfy an evidence-based suspicion of guilt before interrogating suspects. CONCLUSIONS: Implementing the evidence-based suspicion practice can help police reduce false confessions, reallocate investigation time and resources, and assist prosecutors in building strong cases for trial. Likewise, researchers should expand the empirical and legal questions they ask and incorporate priors into their interrogation experiments to improve the generalizability of findings to the criminal justice system. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Why suspects confess: The power of outcome certainty.

OBJECTIVE: In custodial interrogations, suspects tend to give disproportionate weight to immediate outcomes relative to future outcomes when deciding whether to confess or deny guilt. The current research examined whether the perceived (un)certainty of an immediate outcome influences suspects' short-sighted confession decisions. HYPOTHESES: We hypothesized that suspects are more likely to make short-sighted confession decisions when an immediate punishment is certain versus uncertain and that the effects of a certain immediate punishment become stronger the longer suspects are interrogated. METHOD: Using the repetitive question paradigm, college student participants (N = 164, 57% women, 87% Caucasian, M age 18.9 years) admitted or denied 20 illegal and unethical behaviors in an interview. Participants' admissions and denials received either an immediate punishment (answering repetitive questions) or a future punishment (meeting with a police officer in several weeks to discuss their misconduct). In addition, we manipulated participants' perceptions of the immediate punishment to be either certain or uncertain. RESULTS: Participants showed greater short-sightedness in their admission decisions when they perceived the immediate punishment to be certain versus uncertain. Moreover, the influence of the certain immediate punishment on participants' admission decisions tended to increase over time. CONCLUSIONS: These findings provide empirical evidence that the certainty of immediate outcomes may contribute to suspects' shorted-sighted confession decisions. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An expected cost model of eyewitness identification.

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. (PsycINFO Database Record (c) 2019 APA, all rights reserved).