The Differences in Gaze Behaviour Over Time and the Effects of Experience in Crime Scene Investigation

Crime scene investigation is a critical component of the justice system, and errors in evidence collection can lead to miscarriages of justice. This exploratory study examined gaze behaviours of trainee forensic investigators during a 2-week burglary investigation training at the Dutch Forensic Investigation Academy. Four participants, varying in prior experience, investigated multiple mock crime scenes while wearing eye-tracking glasses and provided feedback through semi-structured interviews. A repeated-measures design compared gaze behaviours at the beginning (T1) and end (T2) of training, measuring fixation duration, saccade duration, and saccade amplitude, with prior experience as a potential moderator. Due to the very small sample size, the study was substantially underpowered, and results should be interpreted with caution. Paired-samples t-tests revealed no significant differences in gaze metrics between T1 and T2, although moderate-to-large effect sizes suggest potential trends that may not have been detectable. Mixed-design ANOVA indicated that experienced participants showed smaller changes in gaze behaviours over time, with a significant interaction for saccade duration. Qualitative findings highlighted that participants found reviewing their eye movements informative but emphasized the need for feedback from experienced trainers to interpret data effectively. Participants also reported that expectations about the crime type and scene familiarity influenced their visual strategies. These findings suggest that while training may influence gaze patterns, prior experience, task expectations, and scene familiarity likely shape observed behaviours as well. The study highlights the potential value of eye-tracking feedback in forensic training while emphasizing the need for cautious interpretation of results due to limited statistical power.