As anyone who watches Dr. Phil has surely learned, standard polygraph tests measure responses such as blood pressure, pulse, and respiration rate to detect anxiety associated with guilt or lying. But a new kind of lie detector test could skip the psychophysiological gauges and head straight to the brain for answers on a subject's veracity.
New Scientist pointed us to a patent filed with the World Intellectual Property Organization that proposes detecting lies via near-infrared spectroscopy. Basically, a device would shine near-infrared light through the scalp and skull into certain parts of the brain. Seeing how much light reflects back would indicate oxygenation levels, which vary depending on how active the brain is at a given point and could yield information on the neural pathways underlying the cognitive as well as the emotional aspects of deception.
To measure the light, the patent filers, headed up by Dr. Scott Bunce, a professor of psychiatry at Philadelphia's Drexel University College of Medicine, have come up with a flexible sensing device that would fit around the head. Neural activity could be transmitted to a processor through wired or wireless means, according to the patent, and results could be made available after post-test averaging, or in real time, while the subject is being tested.
The inventors cite heightened reliability as the main advantage of their method. Conventional polygraphy, they say, suffers from a lack of specificity in differentiating guilt from fear or anxiety, and that can contribute to an unacceptably high level of false positives.
Further, they say, conventional polygraphy is subject to inherent sources of variability, such as the question format and personality factors relating to the examiner and subject (a number of sites on the Web even offer tips for beating a polygraph, suggesting some people may not experience the stress generally assumed to be associated with lying).
Another advantage of the near-infrared test, Bunce and team say: the headband would be inexpensive and easy to transport. According to the patent filing, research and development of the invention was sponsored by the U.S. Office of Naval Research and Department of Homeland Security, which means we might one day see these on the battlefield.