Langleben gave male undergraduates an envelope containing
two playing cards. The students were told to lie about one card. As in
Kozel’s experiment, subjects were offered a monetary reward for
successful deception. Using fMRI, Langleben was able to identify 90% of
deceptive responses and 93% of truthful ones.
Although Kozel and Langleben employed different experimental
designs and approaches to analyzing scanner data, they came to strikingly
similar conclusions. “The patterns seem to be almost identical,” Langleben
says. Subjects who lied had increased activation in the prefrontal cortex,
particularly the right orbitofrontal area, just above the right eye.
Kozel and his mentor Mark George are now conducting
a study that should more closely mimic real-world deception. Investigators
in this experiment won’t know which, or how many, subjects are lying.
Steve Laken, chief executive of Cephos Corp., hopes to launch the technology
commercially this year. Although “all the three-letter agencies” are
interested, according to Laken, he predicts the first client will be a
civil or criminal defendant who wants to prove he is telling the truth.
Initially, Laken thinks, the scans should add to witnesses’ credibility
but won’t be seen as guarantees of veracity. Still, he says, fMRI
lie detection could become a “few hundred million” dollar
business within five years.
Kozel, now at the University of Texas Southwestern
Medical Center, is investigating an idea that would take the technology
even further. With George, he proposes combining fMRI scans with something
called transcranial magnetic stimulation (TMS)—a magnetic wand applied
to the outside of the skull that induces an electrical field in the brain
area beneath it. By interfering with the normal functioning of a specific
brain region, the current generated by TMS can temporarily disable that
area. TMS is being tested as a treatment for several neuropsychiatric
conditions. Kozel and George suggest using fMRI to locate the part of
the brain involved in deception and then employing TMS to shut it down—rendering
a subject unable to lie. Even if it works, Kozel warns, it will require
extensive testing to ensure proper use.
As a traveler approaches an airport security checkpoint,
a screener asks, “Did you pack this bag yourself?” The traveler
answers yes, but the screener is suspicious. Politely but firmly, he says, “Please
step over to the scanner.”
The size and cost of MRI machines may always limit
their deployment, but they’re not the only option for finding out
whether someone is telling the truth. Optical sensors operating at near-infrared
wavelengths could be cheaper and more portable. A research team at Drexel
University in Pennsylvania, led by Scott Bunce, an assistant professor
of psychiatry, has developed a small panel with four light sources and
12 detectors. The device is placed on the foreheads of volunteers, who
participate in a playing card experiment.
Near-infrared light easily penetrates most tissue,
but certain wavelengths absorbed by hemoglobin can be used to detect increased
oxygenation—a marker of regional activity in the brain. In the playing
card test of deception, “we could correctly classify 20 out of 21
individuals,” says Bunce. He calls the current apparatus “field
deployable,” though it requires direct contact with—and the
cooperation of—the subject.
Meanwhile, Britton Chance of the University of Pennsylvania,
who invented the panel used in the Drexel research, is working on a system
that operates several meters from the subject’s forehead—“with
or without the subject’s knowledge.” Chance, too, is exploring
commercial applications and has formed a company, Non-Invasive Technology.
He hasn’t published detailed studies, however, because he says security
agencies interested in his work don’t want him to reveal too much.
While these technologies progress, another approach
has already found its way into the courts. Larry Farwell is the founder
of Brain Fingerprinting Laboratories, which markets the use of electroencephalogram
readings to assess familiarity with certain information. Farwell’s
technology has been extensively covered in the media, especially in connection
with one murder case.
On July 22, 1977, in Council Bluffs, Iowa, a night
watchman was killed by a shotgun blast. A young black man, then 19, was
found guilty of first-degree murder. The man maintained his innocence,
and 25 years later, brain fingerprinting was admitted as evidence in his
attempt to obtain a new trial.
To conduct the brain fingerprinting, Farwell visited
the man in the Iowa State Penitentiary. Three electrodes, placed against
the convict’s scalp, monitored his brain as he watched a series
of short phrases flash across a screen. The phrases had been designed
to probe knowledge of the crime scene and details of the convict’s
alibi.
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