Date of Degree

9-2021

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor

Saul Kassin

Committee Members

Deryn Strange

Steven Penrod

Emily Balcetis

Vanessa Edkins

Subject Categories

Cognitive Psychology | Law and Psychology | Social Justice | Social Psychology

Keywords

decision-making, plea bargaining, anchoring, cognitive bias

Abstract

Strategic overcharging, a practice that some prosecutors readily employ to threaten defendants with excessively severe sentences, undermines the Sixth Amendment right to trial by coercing defendants to plead guilty rather than face penalties disproportionate to their alleged misconduct. Legal scholars and psychologists have long suggested that strategic overcharging may elicit powerful anchoring effects that bias defendants’, but not attorneys’ evaluations, of the plea offer. The current research sought to examine (a) the extent to which mock defendants and legal professionals were susceptible to the anchoring bias, (b) elucidate the mechanism underlying susceptibility to the anchoring effect in plea contexts, and (c) test the efficacy of debiasing strategies aimed toward combating reliance on heuristics and improving information processing. Across three experiments, mock defendants (Study 1; N = 479), practicing criminal defense attorneys (Study 2; N = 155), and mock attorney-client pairs (Study 3; Npairs = 265) were willing to accept longer maximum jail sentences to avoid a trial conviction when exposed to a higher versus moderate trial sentence including when trial sentences were presented as unrelated to their case (Study 1; i.e., the number of months left for an acquaintance to graduate from law school). Strikingly, these results demonstrate that increasing the threatened trial sentence increased decision-makers’ willingness to accept (or recommend) higher maximum sentences without also increasing their perceptions of the severity of the crime, the strength of the evidence favorable or unfavorable to their case, or their likelihood of conviction at trial. Anchor-biased sentencing judgments, in turn, explained decision-makers choice to accept prosecutors’ discounted offers — even when actual defendant culpability did not (Study 2). In Study 3, making attorney-client pairs accountable for their decision-making increased their willingness to elaborate on their ideas and the number of case-relevant arguments jointly discussed but did not attenuate their vulnerability to the biasing effect of the anchor. In Study 2, debiasing instructions to generate only mitigating evidence contradicting the appropriateness of a highly threatening trial sentence attenuated the anchoring effect by leading defense attorneys to recommend lower maximum sentences and greater rejection of the plea offer. This research supports the troubling conclusion that threatened trial sentences lead legal decision-makers to raise the bar for what they consider to be an acceptable sentence and that raising that bar causes defendants’ and attorneys to accept plea offers they would not otherwise accept or recommend. These findings reinforce the need for policies that curtail the immense discretionary power of prosecutors to coerce plea decisions.

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