Term of Award

Summer 2011

Degree Name

Master of Science in Experimental Psychology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Psychology

Committee Chair

Amy Hackney

Committee Member 1

C. Thresa Yancey

Committee Member 2

Rebecca Ryan


Many people believe that the insanity defense is used to avoid responsibility for committing a crime and that it returns dangerous individuals back to the streets. Due to the fact that it is difficult to separate such pre-existing attitudes from evidence presented throughout the trial, many jurors use their attitudes to assist them when deciding a verdict and punishment. For example, Steblay, Hosch, Culhane & McWethy (2006) found that not only is it difficult for jurors to disregard information that is not relevant or presented during trial, but that pre-trial information and attitudes can actually influence their verdict. The present study examines how dispositional instructions affect juror decision making in an insanity case. Participants completed a scale that assessed their attitudes toward the insanity defense and read a case description, determined a verdict, and recommended a sentence. Participant's attitudes toward the insanity defense influenced their verdict suggestions and recommended sentences. The type of dispositional information given to participants affected the amount of knowledge about defendants using the insanity defense, but did not affect verdicts or sentences. The implications of dispositional information presented to participants are discussed as well as the influence of pre-existing attitudes towards the insanity defense on verdict determination.

Research Data and Supplementary Material