Eye tracking technology could reveal if suspect is lying about recognition

Law enforcement authorities may soon be able to tell whether a suspect is lying about recognising someone they know, following a study at the International Centre for Research in Forensic Psychology.

Using eye tracking technology, academics found that people’s eyes moved in a different pattern when looking at faces they recognised.

The researchers modified a memory detection technique known as the Concealed Information Test (CIT) to conduct the research. The CIT differs from traditional lie detection techniques that attempt to directly assess guilt based on arousal.

The researchers used the EyeLink II system, which consists of three miniature cameras mounted on a headband. One head-tracking camera is used to detect infrared markers in the world, while two eye cameras focus on the left and right eyes respectively.

The academics recorded the eye movements of 59 participants while looking at 200 digital colour photographs of familiar and unfamiliar faces and those only seen briefly before the experimental trials. Sometimes the participants lied about whether they recognised the photos, sometimes they told the truth.

“When a participant looked at a face they recognised their eyes moved in a different pattern with fewer fixations,” said lead author Ailsa Millen, a research and teaching fellow from the Face Research Laboratory at University of Stirling. “There is substantial evidence to suggest that this pattern is involuntary, which means it could be hard to control or fake.”

Millen told PE that she plans to continue with the research to further assess the reliability of the protocol under different test conditions. For example, when faces are not so well known and when individuals try to beat the test.

“We plan to first build our evidence base before considering its efficacy in real world criminal cases,” she added.

The paper, ‘Tracking the truth: the effect of face familiarity on eye fixations during deception’, will be published in the Quarterly Journal of Psychology: Special Edition on Face Leaning.