Posted on 11/12/2001 4:49:55 PM PST by vannrox
Brain scans can reveal whether someone is lying or telling the truth, US researchers have discovered. When people lied, fMRI (functional magnetic resonance imaging) scans revealed significant increases in activity in several brain regions.
Daniel Langleben and his colleagues at the University of Pennsylvania hope fMRI could be used for more accurate forensic lie detection. The widely used polygraph test is based on changes in heart rate, blood pressure, breathing and the electrical resistance of the skin. But these factors can vary widely among individuals, making it more difficult to establish whether someone really is telling the truth.
Langleben's team gave 18 people an object to hide in their pockets. They were then shown a series of pictures, including one of the object itself. As each picture was presented, the participants were instructed to deny that it matched their hidden object.
When there was a match, and the person was lying, activity in several regions increased. This included the anterior cinglate, which is associated with response inhibition and error monitoring, and the adjacent right superior frontal gyrus, which plays a key role in attention.
The results suggest there is a "localised brain correlate of deception", the team says.
Saint Augustine
"The fact that deception requires extra work in a number of brain regions may indicate that the deception involves inhibition of the 'default' response - truth," adds Langleben. "Interestingly, this agrees with the traditional definition of deception dating back to Saint Augustine: 'Deception is denial of truth'."
Previous attempts to use fMRI to identify brain changes when someone is lying have failed. Langleben suspects that the simplicity of the task used in his team's experiment may help explain their success.
"The main strength of our study was adapting a simple and very well known test that has been used forensically and in research to detect deception with polygraphs and EEGs since the 1950s," he told New Scientist.
Cultural differences
However, more work is necessary before fMRI lie detection could be used for legal purposes, he says.
"Our study shows only an average difference in brain activity between lying and telling the truth in a group of young and healthy English-speaking people. In order to determine whether fMRI can be used to detect deception in any individual, much larger groups of different ages, cultures and socio-economic status should be studied."
Using fMRI also involves using large, expensive scanners, making it much less practical to use than a polygraph test.
Langleben presented his work at the Society for Neuroscience annual meeting in San Diego.
Noslrac
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