First Evidence of Brain Abnormalities Found in Pathological Liars

September 30, 2005

Contact: Usha Sutliff (213) 740-0252 or

USC study shows structural differences in the area of the brain that enables
most people to feel remorse.

A University of Southern California study has found the first proof of
structural brain abnormalities in people who habitually lie, cheat and
manipulate others.

While previous research has shown that there is heightened activity in the
prefrontal cortex — the area of the brain that enables most people to feel
remorse or learn moral behavior — when normal people lie, this is the first
study to provide evidence of structural differences in that area among
pathological liars.

The research — led by Yaling Yang and Adrian Raine, both of the USC College
of Letters, Arts and Sciences — is published in the October issue of the
British Journal of Psychiatry.

The subjects were taken from a sample of 108 volunteers pulled from Los
Angeles’ temporary employment pool. A series of psychological tests and
interviews placed 12 in the category of people who had a history of
repeated lying (11 men, one woman); 16 who exhibited signs of antisocial
personality disorder but not pathological lying (15 men, one woman); and 21
who were normal controls (15 men, six women).

"We looked for things like inconsistencies in their stories about
occupation, education, crimes and family background," said Raine, a
psychology professor at USC and co-author of the study.

"Pathological liars can’t always tell truth from falsehood and contradict
themselves in an interview. They are manipulative and they admit they prey
on people. They are very brazen in terms of their manner, but very cool
when talking about this."

Aside from having histories of conning others or using aliases, the
habitual liars also admitted to malingering, or telling falsehoods to
obtain sickness benefits, Raine said.

After they were categorized, the researchers used Magnetic Resonance
Imaging to explore structural brain differences between the groups. The
liars had significantly more "white matter" and slightly less "gray matter"
than those they were measured against, Raine said.

Specifically, liars had a 25.7 percent increase in prefrontal white matter
compared to the antisocial controls and a 22 percent increase compared to
the normal controls. Liars had a 14.2 percent decrease in prefrontal gray
matter compared to normal controls.

More white matter — the wiring in the brain — may provide liars with the
tools necessary to master the complex art of deceit, Raine said.

"Lying takes a lot of effort," he said.

"It’s almost mind reading. You have to be able to understand the mindset of
the other person. You also have to suppress your emotions or regulate them
because you don’t want to appear nervous. There’s quite a lot to do there.
You’ve got to suppress the truth.

"Our argument is that the more networking there is in the prefrontal
cortex, the more the person 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.

Pathological liars have a surplus of white matter, the study found, and a
deficit of gray matter. That means they have more tools to lie coupled with
fewer moral restraints than normal people, Raine said.

"They’ve got the equipment to lie, and they don’t have the disinhibition
that the rest of us have in telling the big whoppers," he said.

"When people make moral decisions, they are relying on the prefrontal
cortex. When people ask normal people to make moral decisions, we see
activation in the front of the brain," he explained. "If these liars have a
14 percent reduction in gray matter, that means that they are less likely
to care about moral issues or are less likely to be able to process moral
issues. Having more gray matter would keep a check on these activities."

The researchers stopped short of asserting that these structural
differences account for all lying.

"This is one of the components," Raine said.

"The findings need to be replicated and extended to other parts of the
brain. What are the other neurobiological processes?

"We haven’t had studies like this. It’s exciting to us because it’s a
beginning study, but we need a lot more to flesh out this discovery."

Yang, the study’s lead author, said the findings eventually could be used
in making clinical diagnoses and may have applications in the criminal
justice system and the business world.

"If [the findings] can be replicated and extended, they may have long-term
implications in a number of areas," said Yang, a doctoral student in the
USC department of psychology’s brain and cognitive science program.

"For example, in the legal system they could potentially be used to help
police work out which suspects are lying. In terms of clinical practice,
they could help clinicians diagnose who is malingering — making up
disability for financial gain.

"And also in business, they could assist in pre-employment screening,
working out which individuals may not be suitable for hiring.

"But, right now, I have to emphasize that there are no direct practical
applications," she said.

In their journal article, the authors mention that separate studies of
autistic children — who typically have trouble lying — have showed the
converse pattern of gray matter/white matter ratios.

"The facts that autistic children have difficulty lying and also show
reduced prefrontal white matter constitutes the opposite but complementary
pattern of the results compared to adults with increased prefrontal white
matter who find it easy to lie," the researchers wrote.

"Although autism is a complex condition and cannot be taken as a model for
lying, these results…converge with current findings on adult liars in
suggesting that the prefrontal cortex is centrally involved in the capacity
to lie."

The other researchers were Susan Bihrle and Lori LaCasse, also of the USC
College’s psychology department, Patrick Colletti of the Keck School of
Medicine of USC’s department of radiology and Todd Lencz of Hillside
Hospital’s department of research.