spots give away lying eyes
Technology Research News
You can't always see a person blush, but
a computer that tracks heat changes can sense even subtle shifts in the
amount of blood in the capillaries that lie just under the skin.
Researchers from the Mayo Clinic and Honeywell Laboratories have come
up with a way to measure these heat changes in a person's face in order
to tell whether the person is lying or telling the truth.
The system consists of a high-definition thermal imaging camera and a
computer. The camera takes pictures of heat emanating from a subject's
face, and the computer provides a quick analysis of any changes.
Monitoring blood changes in the face is similar to the traditional polygraph
exam, according to James Levine, a consultant at the Mayo Clinic. The
polygraph lie detector test measures changes in a subject's breathing,
pulse rate and blood pressure. It also measures sweating by sensing changes
in skin conductance via electronics attached to the skin.
The thermal method measures infrared lightwaves, or heat, around the person's
face. The infrared light shows up on the computer screen as red areas.
The theory behind using thermal changes in a person's face to detect lying
is similar to the principal behind the polygraph. When someone is not
telling the truth there is likely to be instantaneous warming around the
eyes, which is probably a natural response produced by the sympathetic
nervous system, said Levine.
The thermal method is as accurate as traditional polygraph tests, according
to Levine. It is also faster than polygraph tests and doesn't require
the subject to be connected to a device, he said.
The researchers tested their theory and the system at the U.S. Department
of Defense Polygraph Institute. Twenty volunteers were randomly assembled
into two groups. One group was instructed to stab a mannequin, take $20
from it, then lie about what took place.
The thermal imaging system correctly identified six of eight of the subjects
who were lying, and 11 of 12 who were innocent. The subjects were also
put through traditional polygraph tests, which correctly identified the
same number of guilty subjects, but correctly identified only eight of
the 12 innocent subjects.
Thermal imaging operators would not need the type of training to carry
out the tests that traditional polygraph tests require, according to Levine.
"The technique sounds interesting and promising," said Christoph Koch,
a professor of cognitive and behavioral biology at the California Institute
of Technology. "For mass security and screening applications, you need
a technology that can rapidly, at low-cost and with a low false alarm
rate, screen people."
The accuracy of polygraph methods is controversial, said Koch. However,
if the thermal imaging technique is faster than polygraphs and if it is
less prone to label truthful statements lies it is worth investigating
further, he said.
The researchers are continuing to test the method and are aiming to turn
it into a practical security application, said Levine.
Levine's research colleagues were Ioannis Pavlidis From Honeywell Laboratories
and Norman L. Everhardt from the Mayo Clinic. They published the research
in the January 3, 2002 issue of Nature.
Timeline: 2-4 years
TRN Categories: Computer Vision and Image Processing; Applied
Story Type: News
Related Elements: Technical paper, "Seeing through the Face
of Deception," Nature, January 3, 2002.
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