Jury: Behavioral Aspects - How Jurors Evaluate Evidence

The traditional legal model of the jury trial portrays jurors as passive recipients of the evidence and legal instructions. However, empirical studies of jury behavior find jurors to be active processors of incoming information. Early models of jury decision-making included (1) "averaging models," in which jurors assess and weigh each piece of evidence, combining the results to reach a verdict and (2) "Bayesian models," in which jurors consider and evaluate each new piece of information, revising their position on the appropriate verdict in light of their prior position and the additional evidence. These formal models have enjoyed limited success as descriptions of how jurors actually decide cases.

Explanation-based models of jury decisionmaking, such as Pennington and Hastie's story model, provide an account of jury behavior that comports better with empirical evidence about jury behavior. Consistent with the story model, jurors do not simply record and store the evidence for later use as they receive it. Rather, they actively select and organize the trial evidence to construct a story about what happened. The story they construct is based on the evidence, but jurors also use it to fill in gaps in the evidence by drawing inferences based on their understandings of how the world works. Jurors arrange evidence in the form of a sequence of motivated human actions that include important events, the circumstances of the case, inferences about character, and the parties' motivations and states of mind. By influencing jurors' understanding of what took place, the order in which facts are presented (i.e., in story order rather than witness order) can affect verdicts. No studies have investigated whether the story model provides a reasonable account of decision-making by judges as well as jurors.