Bourgeois, M. J., Horrowitz, I. A., ForsterLee, L., & Grahe, J. (1995). Nominal and interactive groups: Effects of preinstruction and deliberations on decisions and evidence recall in complex trials. Journal of Applied Psychology, 80, 58-67.
Two studies assessed the effects of preinstruction on decision making in simulated civil trials. In Study 1, substantive instructions were presented before the evidence, after the evidence, before and after the evidence, or not at all to nominal jurors who did not deliberate and to interactive jurors who did deliberate. Preinstructed nominal jurors differentiated among the plaintiffs in awarding damages, whereas postinstructed nominal and interactive jurors did not. Group discussion and preinstruction augmented damage awards and improved recall of evidence only for preinstructed jurors. Study 2 suggested that substantive preinstruction engaged a proplaintiff bias when trial evidence was technically difficult but enhanced systematic processing when the evidence was presented in less complex language.
<1>Preinstructed jurors awarded higher damages after deliberation and recalled evidence better than jurors not instructed or postinstructed. <2>Preinstruction increased verdicts for defense when testimony non-technical; increased verdicts for plaintiff when technical.