Trauma symptoms, memory accuracy, and eyewitness suggestibility: a mediation analysis in a non-clinical sample

Eyewitness testimony is a key component of legal decision-making, yet it is highly vulnerable to cognitive and psychological influences. While trauma has been associated with alterations in memory processes, its role in eyewitness suggestibility remains unclear. In particular, it is not well understood whether trauma influences suggestibility directly or through related mechanisms such as dissociation or memory accuracy. The present study aimed to examine the relationship between trauma level and eyewitness memory performance, with a specific focus on memory accuracy and susceptibility to suggestive questioning, as well as the roles of dissociation and emotional arousal.

Participants were 104 undergraduate students categorized into low- and high-trauma groups based on their scores on the Posttraumatic Stress Diagnostic Scale (PDS). After viewing a traffic accident video, participants completed a 20-item post-event questionnaire consisting of yes/no questions designed to assess memory accuracy and susceptibility to suggestive questioning. The questionnaire included both accurate and misleading items. Correlational and mediation analyses were conducted as primary analyses using continuous trauma severity scores. Group-based descriptive comparisons were also conducted for exploratory purposes.

Individuals with higher trauma levels demonstrated significantly lower memory accuracy compared to those with lower trauma levels. Trauma was positively associated with dissociation and modestly associated with suggestibility, while memory accuracy showed a strong negative relationship with suggestibility. However, trauma group differences were not significant for suggestibility or response bias. Mediation analysis revealed that memory accuracy fully mediated the relationship between trauma and suggestibility, consistent with a pattern of full indirect association between trauma severity and suggestibility via memory accuracy. In contrast, dissociation did not emerge as a significant mediator. Additionally, emotional arousal was not significantly related to trauma, memory accuracy, or suggestibility.

These findings suggest that trauma-related vulnerability to suggestive questioning appears more strongly associated with cognitive factors, particularly memory accuracy, than with dissociative processes. The results highlight the importance of memory accuracy as a cognitive mechanism relevant to eyewitness reliability and underscore the value of considering individual differences in cognitive functioning when evaluating testimony from trauma-exposed individuals.