Sunday, 29 March 2009

BOLD-faced lie detection

You wouldn't know it from the claims of companies like No Lie MRI, but we're a long way off being able to use brain scans to detect reliably whether a person is lying or not. Nonetheless, cognitive psychologists are busy beavering away in the background, testing the ways that brain activity varies when people lie compared with when they tell the truth. One such study has just been published, claiming to be the first to investigate deception in the context of face recognition.

Sujeeta Bhatt and colleagues scanned the brains of 18 participants undergoing a simple task designed to simulate a police line-up. The researchers compared brain activity across three conditions: when the participants pointed out truthfully which face from three they'd seen earlier; when they lied and pointed to a new face rather than the one they'd seen earlier; and finally a condition where all the faces were new but the participants lied and pretended to have seen one of them before.

No single brain area was active when the participants lied compared with when they told the truth. However, a network of frontal and parietal regions were more active in the lying conditions. This network included the dorso- and ventro- lateral prefrontal cortices, the superior frontal gyri, and the anterior cingulate gyrus, all of which are found at the front of the brain. These areas are known to be involved in working memory, response selection and error monitoring. In the parietal lobe, the precuneus - an area known to be involved in visual imagery- also showed increased activity during lying.

"It is possible that the frontal and parietal area activation seen in the current study is a result of the complex interplay of working memory, response inhibition, sustained attention, and mental calculations necessary for our subjects to make a deceptive response," Sujeeta Bhatt and her colleagues said.

However, they further acknowledged that like other studies in this field, their findings are limited by the fact that their participants were not under anything like the kind of pressure that is normally associated with lying in real life. Also, don't forget studies like this one are looking at average group differences in lying versus truth-telling conditions, rather than studying an individual, as would presumably be required most often in real-life settings. That said, this study makes a worthy contribution to an emerging field that piece by piece will surely one day soon lead to a brain-based lie detection system - watch this space!
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ResearchBlogging.orgBhatt, S., Mbwana, J., Adeyemo, A., Sawyer, A., Hailu, A., & VanMeter, J. (2009). Lying about facial recognition: An fMRI study Brain and Cognition, 69 (2), 382-390 DOI: 10.1016/j.bandc.2008.08.033

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

There are plenty of popular science articles about the potential of brain-based lie detection. Here's a sample:

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