Publication Date


Advisor(s) - Committee Chair

Christopher Peters, Frederick Grieve, Carrie Trojan

Degree Program

Department of Psychological Sciences

Degree Type

Master of Arts


The misconceptions regarding the insanity defense have often left bias rampant within the court room. Within this study, the goal was to understand the relationship between education via an expert witness and how it changes one’s verdict on a case where the insanity defense is used. Participants were given a vignette regarding the circumstances of an NGRI defense case, and then randomly assigned to a control video and a myth video. The control video talked about the circumstances around assessment, and insignificant details of the case, while the myth version discussed the common myths and misconceptions regarding the insanity defense. Each participant was then given a series of scales to measure political beliefs, emotionality, knowledge on the NGRI plea, and bias towards those with mental illness. The majority of participants chose their verdict as NGRI, which is contrary to some of the current literature. The biggest point of significance came within Bias. Bias was the most significant factor in predicting one’s verdict. An indirect link was also found between the condition and verdict. The condition each participant was in effected their knowledge on the insanity defense, which in turn determined one’s verdict decision. The results found within this study show the pervasiveness of bias within the courtroom and may aid in directing future studies towards resolving bias within the courtroom.


Clinical Psychology | Psychology | Social and Behavioral Sciences