Reducing the effects of juror bias.

Kaplan, M. F., & Miller, L. E. (1978). Reducing the effects of juror bias. Journal of Personality and Social Psychology, 36, 1443-1455.

Predeliberation guilt ratings strongly affected by evidence strength and affected somewhat by annoying attorney/judge behavior. Deliberation produced polarization shift in direction consistent with evidence; bias due to 3rd-party behavior reduced greatly by deliberation.

Proposes a theoretical framework for relating bias to a juror’s ultimate judgment. In this framework, bias, in the sense of positivity or negativity of a prejudgmental disposition, is integrated with the degree of guilt appearance of the evidential information. The 2 components, bias and evidence, are inversely weighted, so that increasing the importance of one decreases the effective importance of the other. In 2 experiments with 192 undergraduates, the effects of trait biases in simulated jurors, selected for their harshness or leniency toward criminals, were reduced by conditions that increased the reliability and trustworthiness of trial evidence. Situational biases were induced in a 3rd experiment with 96 undergraduates by trial conditions designed to annoy jurors, but their effects were ameliorated by a short period of deliberation. These bias-reducing procedures are interpreted as indirectly dealing with bias by increasing the salience of the information taken into account in judgment formation. Some implications regarding trial conditions that facilitate or inhibit manifestation of bias are discussed.