Charged Up and Anchored Down: A Test of Two Pathways to Judgmental and Decisional Anchoring Biases in Plea Negotiations

Prosecutors sometimes threaten defendants with disproportionately severe potential trial sentences (PTS) to coerce their plea acceptance. Three experiments tested whether the PTS acts as an anchor that biases evaluations of the plea deal at deep (vs. shallow) processing level by encouraging asymmetric consideration of information consistent—but not inconsistent—with the appropriateness of the PTS. I expected that a high (vs. moderate) PTS would lead to greater plea acceptance by increasing maximum acceptable sentencing preferences and influencing evidence appraisals. I tested two anchor debiasing strategies: selective consideration of anchor-inconsistent evidence (Consider-the-Opposite Strategy; COS) and holistic consideration of all evidence (via process accountability). Participants read detailed information about their criminal case and the PTS (high or moderate) before indicating their maximum sentencing preferences, evaluating case attributes, and rendering a plea decision. Mock defendants (Experiment 1; N = 479; drelevant= 0.83), defense attorneys (Experiment 2; N = 155; dpre-COS= 1.19), and mock attorney-client pairs (Experiment 3; Npairs= 265; dunaccountable= 0.60) were willing to accept (or recommend) longer sentences when presented with a higher (vs. moderate) PTS—even when the PTS was irrelevant to their case (Experiment 1; dirrelevant= 0.64). Mediation analyses across all studies demonstrated that higher maximum sentencing preferences were, in turn, associated with greater willingness to accept a plea deal, but not with biased evaluations of evidence strength. Selective consideration of evidence inconsistent with the high PTS attenuated anchoring effects on sentencing preferences (Experiment 2; dpost-COS= 0.75) and plea recommendations but discussing more evidence did not (Experiment 3; daccountable= 0.68). This work challenges the law’s assumption that defense attorneys can debias defendants’ cognitive errors and preliminarily proposes easy-to-implement debiasing solutions to overcharging. Key words: anchoring, motivated information processing, expertise, plea bargaining, judgment and decision-making