Eye-tracking technology in combination with the Guilty Knowledge Test in police investigations

The current research examined whether people who are in the possession of guilty knowledge differ in their eye-movement patterns in comparison to innocent people who are not in the possession of guilty knowledge. The design of the study was a between-subjects design with three conditions: guilty condition, accomplice condition, and control condition. Participants imagined that they either were guilty of hiding synthetic drugs, were an accomplice of hiding synthetic drugs in exchange for 10.000 euro, or did not have guilty knowledge (control condition). Then, participants were shown a picture of the crime scene during an interrogation, where the guilty- and accomplice conditions were asked to lie and the control condition was asked to tell the truth. While participants looked at the picture, their eye-movements were tracked. The results of the current study show no statistical differences between the conditions, which implies that guilty people and innocent people do not differ in their eye-movement patterns. This study also revealed other valuable insights for future research. It contributes in emphasizing the importance of using a strong manipulation during experiments, the involvement of participants, and sample size, which should all be taken into account for in future research.