Definition
Jury decision making is the study of how lay decision-makers — typically twelve jurors, in some systems six — combine evidence and deliberation to reach a verdict. The field draws on cognitive psychology (how individual jurors process evidence), social psychology (how group dynamics shape deliberation), and behavioural economics (how biases and heuristics distort judgement).
Research uses three principal methods: jury simulations with mock evidence and student or community participants; post-trial interviews with real jurors (where rules permit); and analysis of verdict statistics across cases. Each method has limits, but converging findings produce a robust picture of how juries actually reason.
Why it matters
Where it shows up
Jury research influences voir dire (selection), the design of jury instructions, judicial decisions about admitting potentially prejudicial evidence, and reforms to deliberation practice (note-taking, juror questions, decision aids). It also features in academic and political debates about jury size, unanimity, and abolition.