Publication Date


Document Type


First Advisor

Kaplan, Martin F.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Psychology


Jury--Psychology; Instructions to juries


The impact of reasonable doubt definition, timing of the instruction to jurors, and time of assessment on recognition memory and defendant evaluations was examined. One hundred three male and 137 female subjects met in groups of up to six persons to view a videotaped trial simulation. Subjects were given requirements of proof instructions either before, after, or both before and after the presentation of evidence. The instructions contained either a strict, lax or undefined definition of reasonable doubt. After taking a recognition memory test (recognition accuracy and reaction time to recognition), subjects made defendant evaluations (verdict-confidence score, probability of commission rating, and the criterion set for conviction) either immediately or 1 week later. Contrary to expectations, there was no effect for timing of instruction on defendant evaluations. Pre-instruction did not produce verdicts and probability of commission estimates which were biased in favor of the defendant. Also, post-instruction did not result in a more dispersed pattern of conviction criterion estimates. Stringency of definition, however, did influence judgments. As expected, higher conviction criterion estimates and more lenient verdicts (when assessed after a delay) were found when the definition of reasonable doubt was more strict. Contrary to expectations, probability of commission estimates were inversely related to definition stringency. As with defendant evaluations, there was also no effect for timing of instruction on recognition memory. The only variable affecting recognition was evidence type. Prodefense evidence was recognized more accurately and quickly than pro-prosecution evidence. The results were discussed in terms of the possible reasons behind the failure of an effect for timing of instruction. It was suggested that the demonstration of a timing effect hinges on subjects' evaluation of a stimulus trial.


Includes bibliographical references (pages [62]-68)


vi, 189 pages




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