A shifty look, desperately avoiding eye contact? Sounds like the behaviour of a guilty person, right?

Well, not according to a new study conducted by psychologists.

Researchers from the University of Sydney found that making direct eye contact towards a victim in a police line-up could sometimes wrongly increase the chances of being picked out as a suspect.

This is because, scientists say, making eye contact increases the perceived familiarity of a face – despite the fact that you may have never seen the person before.

University of Sydney psychologists tested the effect eye gaze had on perceived familiarity.
Psychologists tested the effect eye gaze had on perceived familiarity (University of Sydney)

To add to that, the human brain is sensitive to eye contact and makes a biased selection favouring those who directly hold their gaze.

Jessica Taubert, lead author of the study, said: “In line-up recognition tasks, the face looking directly at you is more likely to look familiar than faces looking away from you.

“This leads to more misidentification errors for direct gaze faces.”

The study, which involved test subjects being shown short video clips of people and then asking to pick them out from a line-up, found those who made mistakes were most likely to pick someone who looked straight at them.

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This bias disappeared when those in the line-up closed their eyes.

Line-ups are often used in eyewitness identification, but results are prone to error. And the main reason for this is overconfidence.

Celine van Golde, co-author of the study, says that because people recognised “friends, family and familiar people so quickly and easily”, confidence was inflated when faces were unfamiliar.

A woman identifying a man in a police line-up.  [url=search/lightbox/7406571] [img]http://richlegg.com/istock/banners/mugshot_banner.jpg[/img][/url] [b][url=search/lightbox/7406571]Click HERE to see my other Line-Up/Mugshot images[/url][/b]
Overconfidence could be one of the reasons why eyewitnesses can often make mistakes in line-up identifications (RichLegg/Thinkstock)

She added: “People tend to overestimate how well they can recognise faces.”

Researchers say small changes in the line-up setting could prevent the bias and lead to a lower misidentification rate in the future.

The full study was published in the journal i-Perception.