Juror Decision Making: Does juror stigma, mental health literacy, or the description of a defendant’s mental health status, impact decision-making in a mock criminal trial?

There has been limited research considering how different types of mental health information can influence juror decisions of guilt. The present study adopted an experimental methodology in which the amount of mental health information presented to contextualise an alleged offence of Criminal Damage was varied. Participants (n=243) were randomly assigned to one of three conditions (‘control’: a mental health explanation could be reasonably inferred but was not directly stated; ‘symptoms only’: clear mental health symptoms were described but no diagnosis; ‘symptoms + diagnosis’: which only differed from the ‘symptoms’ condition by additionally describing the condition as ‘paranoid schizophrenia’). Participants watched a series of videos depicting a fictional criminal trial and were asked to make judgements of guilt. Baseline stigma towards mental health conditions and mental health literacy (MHL) were measured using standardised scales. Guilt ratings were measured as the dependent variable. Regression analyses identified that mental health information, stigma, and MHL were all important predictors of guilt, however interaction effects indicated that people with higher MHL were particularly influenced by increasing mental health information (with guilt judgements decreasing more for those with higher MHL). A particularly notable finding was that even the addition of a diagnosis of paranoid schizophrenia was associated with a reduction in guilt ratings, even after controlling for all other factors. The results are relevant to the way in which mental health conditions are described in the courtroom, and suggestions are made for future research.