Shape of things to comeInfrared lie detector
Rather than measure what are taken to be the symptoms of lying — increased heart and respiration rate, perspiration — new infrared detector measures brain activity
An application for a patent on a new invention has just been submitted, an invention which would make the life of security forces easier: an infrared lie detector. Security services around the world have used lie detectors to lock many people up over the years, but these detectors are of suspect reliability. New Scientist’s Justin Mullins writes that a new way of scanning brain activity may change that.
The long-established polygraph test measures a person’s respiration rate, heart rate, and perspiration. The idea is to detecting anxiety associated with guilt or lying. Simply being anxious — about, say, being interrogated — may well produce similar signals, and some people may be able to learn to beat the test. By some accounts, the results from such tests are no more accurate than guesswork. Scientists believe that measuring brain activity directly is a more promising approach. This is currently achieved using technologies such as functional magnetic resonance imaging or EEGs.
These methods have their own disadvantages, though. EEGs, for example, provide only a very low resolution picture of brain function, and fMRIs are very expensive, while scans are ruined by small movement of the subject. Scott Bunce, at Drexel University’s College of Medicine in Philadelphia, says a better solution is to send near-infrared light through the scalp and skull into the brain and see how much is reflected back. He has designed a special headband that does just that. The amount of reflected light is dependent on the levels of oxygen in the blood, which in turn depends on how active the brain is at that point. This, he says, gives a detailed picture of real-time activity within the brain that can be used to determine whether the subject is lying. The technique is both cheaper and easier to apply than fMRI and gives a higher resolution than an EEG. Note that a similar approach is being used to investigate Alzheimer disease.
It is not yet known whether brain activity can reliably be decoded to reveal deception, but this is another question. Read the infrared lie detector patent application.
