Date of Award

Spring 6-2020

Document Type


Degree Name

Master of Arts (MA)


Forensic Mental Health Counseling



First Advisor or Mentor

Margaret Bull Kovera

Second Reader

Rebecca Weiss

Third Advisor

Steven Penrod


Objective: The current study tests whether jury-eligible adults follow judicial instructions to disregard information about a defendant’s pretrial competency status when deciding whether he is guilty or not guilty by reason of insanity. Hypotheses: It was anticipated, because of the effects of hindsight bias, that defendants who were previously found competent to stand trial would be less likely to be found NGRI than a defendant who previously was deemed incompetent but has been restored to competency for trial. We also predicted that judicial instructions to disregard pretrial competency status would not effectively eliminate the effect of competency status without an accompanying explanation of why it was important to do so. Method: An online convenience sample of jury eligible adults (N = 205) watched a mock trial video in which we varied defendant competency status (competent vs. incompetent) and judicial instructions on how to consider this evidence (no instructions vs. instructions only vs. instructions with an explanation of legal rationale). Jurors gave their verdict (guilty vs. NGRI) and completed a post-trial questionnaire. Results: There was a significant effect of competency status; participants were more likely to render guilty verdicts when the defendant had always been competent to stand trial than when the defendant initially had been found incompetent and received restorative treatment. A similar pattern was found for participants’ ratings of whether the defendant knew that his behavior was wrong and had the ability to comport his behavior with the law. Standard instructions mitigated the biasing effects of competency to stand trial, which was not the case when the instructions were accompanied by an explanation of the legal standard. Conclusions: The pretrial competency status of a defendant affects jurors’ decisions even though it is a legally impermissible consideration. Standard instructions may serve a corrective function in improving juror adherence to legal standards. However, instructions which are too lengthy or too complicated may overwhelm jurors or draw more attention to the irrelevant information, thus increasing its biasing effects.



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