A University of Southern California study has found the firstproof of structural brain abnormalities in people who habitually lie,cheat and manipulate others.
While previous research has shownthat there is heightened activity in the prefrontal cortex – the areaof the brain that enables most people to feel remorse or learn moralbehavior – when normal people lie, this is the first study to provideevidence of structural differences in that area among pathologicalliars.
The research – led by Yaling Yang and Adrian Raine, bothof the USC College of Letters, Arts and Sciences – is published in theOctober issue of the British Journal of Psychiatry.
The subjectswere taken from a sample of 108 volunteers pulled from Los Angeles'temporary employment pool. A series of psychological tests andinterviews placed 12 in the category of people who had a history ofrepeated lying (11 men, one woman); 16 who exhibited signs ofantisocial personality disorder but not pathological lying (15 men, onewoman); and 21 who were normal controls (15 men, six women).
"Welooked for things like inconsistencies in their stories aboutoccupation, education, crimes and family background," said Raine, apsychology professor at USC and co-author of the study.
"Pathologicalliars can't always tell truth from falsehood and contradict themselvesin an interview. They are manipulative and they admit they prey onpeople. They are very brazen in terms of their manner, but very coolwhen talking about this."
Aside from having histories of conningothers or using aliases, the habitual liars also admitted tomalingering, or telling falsehoods to obtain sickness benefits, Rainesaid.
After they were categorized, the researchers used MagneticResonance Imaging to explore structural brain differences between thegroups. The liars had significantly more "white matter" and slightlyless "gray matter" than those they were measured against, Raine said.
Specifically,liars had a 25.7 percent increase in prefrontal white matter comparedto the antisocial controls and a 22 percent increase compared to thenormal controls. Liars had a 14.2 percent decrease in prefrontal graymatter compared to normal controls.
More white matter – thewiring in the brain – may provide liars with the tools necessary tomaster the complex art of deceit, Raine said.
"Lying takes a lot of effort," he said.
"It'salmost mind reading. You have to be able to understand the mindset ofthe other person. You also have to suppress your emotions or regulatethem because you don't want to appear nervous. There's quite a lot todo there. You've got to suppress the truth.
"Our argument is thatthe more networking there is in the prefrontal cortex, the more theperson has an upper hand in lying. Their verbal skills are higher.They've almost got a natural advantage."
But in normal people,it's the gray matter – or the brain cells connected by the white matter– that helps keep the impulse to lie in check.
University of Southern California. "First Evidence Of Brain Abnormalities Found In Pathological Liars." ScienceDaily. ScienceDaily, 2 October 2005. <
www.sciencedaily.com/releases/2005/10/051002115557.htm>.
https://www.sciencedaily.com/releases/2005/10/051002115557.htm