Emotions Overriding Forensic Opinions? The Potentially Biasing Effects of Victim Statements

Forensic experts are frequently advised to gather multiple sources of data, including victim accounts, in criminal cases. This study is the first empirical investigation of whether victim accounts may exert a biasing effect on clinical-forensic opinions. The research employed a completely randomized factorial design to study the effects of aggressive history, diagnosis of antisocial personality disorder (APD), and victim statements on sentencing issues in a Canadian dangerous offender (DO) case. With a sample of 332 Canadian psychiatrists, the study found that victim statements exerted an unexpected effect on DO determinations (Cohen's d=.52) that exceeded the defendant's aggressive history (d=.19) and APD diagnosis (d=.34). The study's implications for gathering victims' accounts are discussed within the framework of forensic evaluations.