Police Tech & Gear
with Tim Dees
The next generation of lie detectors
The Embodied Avatar device is presently being tested on real border crossers in Nogales, Arizona
Not long after the advent of spoken language, someone told a lie.
It might have been “I didn’t do it” or “Of course that animal skin doesn’t make your butt look fat, dear,” but we’ve never stopped telling lies, and picking out truth from deception has been an eons-long problem.
A device undergoing testing by the Department of Homeland Security has a reliability rate of up to 94 percent, and may be the most accurate lie detector in history.
The Embodied Avatar
The system is called the Embodied Avatar. It all but takes over the job of interrogator by having the subject stand in front of a computer monitor integrated with a microphone and two cameras. The first is a high definition visible light camera that adjusts to the subject’s height, and the other is a near-infrared camera that records pupil dilation and gaze direction.
Except for a brief moment when the subject touches a fingerprint scanner, there is no physical connection between the device and the subject.
Experts in the detection of deceptive statements look for physiological changes and movement cues to indicate when someone is lying. The polygraph measures changes in pulse rate, respiration, blood pressure and galvanic skin response (brought on by sweating) to indicate stress associated with trying to get a lie past the examiner.
Operation of a polygraph is as much an art as a science. The polygraph operator has to know when to press a particular question, asking it several different ways, to provoke a stress reaction. Stressing a question too much may produce a false positive.
Recent history shows the polygraph is far from infallible, even in the hands of a skilled operator. Aldrich Ames and Robert Hanssen were both convicted of passing government secrets to foreign powers, and both passed periodic polygraph exams.
There are a few proponents of computerized voice stress analysis, where “microtremors” in the voice betray the telling of a lie. Tests of voice analyzers under controlled conditions put their reliability at about the same level as the toss of a coin.
Clusters of Behavior
Present-day deception experts point to clusters of behavior when people lie. These can include momentary glances away from the focus of the conversation and small changes in facial expressions (“microexpressions”), as well as slight changes in vocal pitch. Some of these are as brief as the blink of an eye, so a human monitor can miss a cue by doing just that.
Paul Ekman is the leading expert in lie detection. There was a TV series, Lie to Me, based on his career. He claims that microexpressions lasting as little as 0.04 seconds can indicate lies 70 percent of the time, with accuracy increasing to almost 100 percent if other cues are recorded.
Judee Burgoon and Jay Hunamaker at the University of Arizona designed the Embodied Avatar using Ekman’s research, replacing the human eye with the multiple unblinking eyes of a computer.
As a disembodied face on a computer display asks questions of the subject, the cameras look for microexpressions, stiffness associated with attempts to “freeze” and inhibit changes, pupil size changes and deviations of gaze angles. The microphones record changes in voice pitch and inflection.
The computerized interrogator asks questions about the truthfulness of information already furnished by the subject — name, addresses, work history, citizenship, criminal offenses, etc. If the machine senses a lie, the subject is referred to a human investigator. If not, they are allowed to go on their way.
The Embodied Avatar is being tested on real border crossers in Nogales, Arizona.
Refinement of the hardware and software is an ongoing process, as the device is still considered to be experimental. If the test is successful, you may see deployment at other United States ports of entry and possibly at U.S. airports for use by the TSA.