Presumption of Innocence: Congruence Bias Induced and Overcome

The American criminal justice system guarantees each citizen the right to a trial by a fair and impartial jury. Because juror biases might impede realization of this guarantee, the law provides a protection for defendants–the presumption of innocence. Three experiments were conducted to assess presumptions of innocence directly. In the first two experiments, subjects were given written descriptions of the defendant and charge; the level of judicial instructions was varied. Results failed to show a presumption of innocence and suggested that biases can be induced by the manipulation of crime congruence to defendant occupation. In addition, biases were not counteracted by specific judicial instructions, and crime congruence affected males and females differently. In a third experiment, the same biasing variable was incorporated into a simulated trial. Subjects viewed videotapes of the trial from jury boxes in a law school's model court room. With the full trial setting, crime congruence did not influence presumptions of innocence. Sex differences were noted again, with females giving higher ratings of guilt, but showing less confidence in their judgments compared to males. Given the strong bias that emerged in the first two experiments, the absence of bias with the full trial setting carries implications for psycholegal research that employs less realistic settings and less authentic material.