Scans Can Detect Lying
(HealthScoutNews) -- You
know the old saying, "You can't lie to yourself"? Now,
brain scans show that adage is all too true.
In findings that could put the lie detector machine out of business,
a new study has found brain scans can detect when someone is lying.
Researchers used functional magnetic resonance imaging (fMRI)
to track the brain activity of 18 college student volunteers who
were given a version of the Guilty Knowledge Test, a method
of interrogation frequently used by law enforcement officials.
The students were given an envelope containing the five of clubs
playing card. They were told to hide it in their pockets and to
deny they had it when asked.
The students then were placed in a fMRI scanner and "interrogated"
by a computer that showed them a series of playing cards accompanied
by the question: "Do you have this card?"
When the students lied, the areas of the brain that play a role
in paying attention and controlling error were much more active
than when the students told the truth. The brain sections include
the anterior cingulate gyrus, located deep in the brain towards
the top of the head, and parts of the prefrontal and premotor
cortexes, both located in the very front of the brain.
"It requires more brain activity to lie than to tell the
truth," says lead study author Dr. Daniel Langleben, assistant
professor of psychiatry at the University of Pennsylvania. ''Truth
is the default position of the brain. It's harder to lie than
to tell the truth because the first thing we need to do to lie
is to suppress something."
The study was presented at the recent national meeting of the
Society for Neuroscience in San Diego.
So what does this mean for the future of catching criminals?
Langleben says more testing is needed, but brain scans could
eventually become the "gold standard" to refine other
methods now used to determine truth and deception.
The most commonly used lie-detecting device now is the polygraph,
an instrument that uses electrodes to measure physiological changes
associated with nervousness, such as increased respiration, heart
rate and perspiration. Presumably, people who are lying are more
nervous than those telling the truth.
But the polygraph is very controversial. Critics say it's not
reliable and that people can easily learn to fool the system.
Researchers around the world are experimenting with newer technologies
to develop more accurate lie-detection methods, including analyzing
movements of eye muscles and "brain fingerprinting,"
a method that measures brain waves called P300. These brain waves
are triggered when someone sees something familiar.
Emanuel Donchin, professor of psychology at the University of
South Florida, in Tampa, says looking for clues about lying by
examining brain scans or brain waves is fraught with problems.
In the experiment using fMRI scans, the researcher found the
students' brains reacted differently to the five of clubs than
to the other cards. But the study did not prove that the difference
in brain activity was the result of lying.
The brain could be reacting to the previous knowledge that the
card had been singled out, Donchin says.
"Lies are not being detected. What is being detected is
an emotional response to an item," Donchin says.
And he cites a real world example. In the Guilty Knowledge
Test, suspects are asked about their knowledge of some aspect
of a crime known only to the guilty person and the police.
Say a wallet was stolen and hidden under an aquarium. The police
ask the suspect a series of questions about the location of the
wallet. (Is the wallet in the cabinet? on the table?)
When the police ask if the wallet is under the aquarium, the
suspect's brain might respond differently to that question. But
this could be because the suspect forgot to feed his fish, or
because, when he was a child, he got into big trouble for knocking
over an aquarium.
"If you respond differentially, you know the item has special
significance, but you don't know that the person is lying,"
What To Do
To read more about polygraphs, check
Antipolygraph.org, which is critical of polygraphs.
You can read more about P300 at
BrainWave Science. And here's a pinup of the
Reference Source 101