Publication Date

Summer 2021

Advisor(s) - Committee Chair

Melissa Baker (Director), Frederick Grieve, and Holli Drummond

Degree Program

Department of Psychology

Degree Type

Master of Arts


This study examined the influence of mental illness on mock juror decisions in a criminal case. With the knowledge that mental illness continues to be highly stigmatized, I hypothesized that the presence of a mental illness in a defendant of a violent crime would have significant effects on participants’ case decisions and their perception of the defendant’s guilt. Participants in the study read a fictional vignette describing a homicide and a defendant in which the defendant’s mental illness diagnosis was varied (major depressive disorder, schizophrenia, borderline personality disorder, no mental illness). Participants were then required to answer 6 questions regarding their perceptions of the defendant’s guilt: verdict decision, confidence in their verdict, guilt rating, choice of punishment, sentencing, and how much responsibility they attributed to the defendant. Results showed that participants gave the defendant with MDD and the defendant with no mental illness with a higher rating of guilt and viewed them as being more able to appreciate the wrongfulness of his actions than the defendants with schizophrenia and borderline personality disorder. There were no significant differences in verdict, punishment, sentencing, or confidence.


Criminology and Criminal Justice | Legal Studies | Psychology | Social Psychology