A UBC Okanagan study shows liars don't give themselves away with a single tell-it's a mix of subtle signs.
Most people know that each time the fictional character Pinocchio lied, his nose would grow.
While a growing nose makes for a fun children's story, a UBC Okanagan researcher says it's hard to know when someone is lying-and there's usually no single facial expression that reveals it.
Dr. Leanne ten Brinke, Associate Professor in UBCO's Irving K. Barber Faculty of Arts and Social Sciences , studies the art of deception. Her latest study revisits her 2012 research, which found that people show several subtle clues when they're lying-not just one, like a growing nose.
"Despite the commonplace nature of deception, humans are poor at detecting lies. Accuracy for deception detection by untrained people is estimated at 54 per cent," says Dr. ten Brinke. "But because justice often depends on our ability to detect lies, past research focused on behavioural cues to try to detect them."
The 2012 paper identified four behavioural cues to deception. The researchers studied public appeals from people pleading for the safe return of a missing relative. In some of these cases, those making the pleas were later found to be responsible for murdering the missing person-turning their emotional appeals on national television into high-stakes act of deception.
In her latest paper, published in Law and Human Behavior , Dr. ten Brinke tested if earlier findings could be applied to new cases to spot deceptive appeals and identify potential murderers.
It appears they couldn't.
"In our earlier research, we combined speech analysis with facial coding and found that signs like a raised eyebrow, a smile, fewer words and more tentative language such as 'maybe' or 'I guess'-all together-could predict truthfulness at 90 per cent accuracy," she says.
Each of these signs comes from deception theory, and the fact that they each add unique information supports using multiple cues to detect lies.
"Highly motivated liars may try so hard to seem believable that they give off even more signs of deception," she adds. "In high-stakes situations, strong emotions can also make it harder for liars to hide of fake their feelings."
Dr. ten Brinke compared the original study with the new one and found mixed evidence for these deception cues across these two sets of cases.
While some cues appeared again, others did not. In the new cases, these behaviours were much less accurate at predicting truth, and overall, they did no better than chance.
"People often think we can spot a liar through certain speech patterns or facial expressions. But this study shows us we shouldn't rely too much on signals that work in one group and assume they apply to everyone, especially in high-pressure situations like police interviews. More studies are needed to know what really works, and we may need to take a more personalized approach."
