Date of Award

2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Psychology

Committee Chair

Lauren Meaux

Committee Member

Jodi Price

Committee Member

Shauna Bowes

Research Advisor

Lauren Meaux

Subject(s)

Jurors--Decision making--Psychological aspects, Criminal intent, Insanity (Law), Insanity defense

Abstract

Juror decision-making in cases involving mental illness is shaped by legal understanding and subjective attitudes. This study examined how juror attitudes and jury instruction type influence the application of mens rea defenses—Not Guilty by Reason of Insanity (NGRI), Diminished Capacity (DC), and Guilty but Mentally Ill (GBMI)—in criminal case vignettes involving defendants with mental health presentations. Enhanced jury instructions improved understanding of mens rea concepts but did not improve the application of these concepts to verdict decisions. Biases against mens rea defenses were associated with DC verdict decisions, with more negative NGRI attitudes predicting less legally accurate but more confident judgments. Factors not related to legal understanding, such as personal attitudes or beliefs about mental illness, may have a stronger influence on jurors' verdict decisions.

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