Pupillary Size in Response to a Visual Guilty Knowledge Test: New Technique for the Detection of Deception

Researchers examined the effects of committing a mock crime on pupillary response (PR) to photographs of crime-scene details. In Experiment 1, 70% of participants with guilty knowledge and 100% without such knowledge were correctly detected. In Experiment 2, electrodermal and PR were recorded. For both measures, target items elicited larger responses than control items for guilty participants, but not for innocent ones. Participants with guilty knowledge also had larger PRs on control items than those without such knowledge. With PR, 50% of those who were guilty and 100% of those who were innocent were correctly identified. With electrodermal data, 55% of guilty and 93% of innocent participants were correctly identified. The results hold promise for the development of a new method of criminal interrogation using PR to a visual guilty knowledge test.