Tag Archive for Polygraph

Some Other Lie Machines – Thermal Scanners, Eye Trackers, Pupillometers And Stress Sniffers

by  • March 6, 2013 • 0 Comments

Other machines that could potentially find their way into law enforcement and homeland security include thermal scanners, eye trackers and pupillometers. Scientists at Dodpi or the Department of defense polygraph institute have created a machine that measures the body’s emissions of heat, light, vibration and other minute changes that happen during lying. One of the tools measures the amount of heat that is released just inside each eye. The theory is that heat increase with lying and stress and this should increase during lying. From this chapter, we know that this machine has severe limitations since not all liars experience stress and fear, and not all honest people lack it. Another machine tracks people’s gaze patterns to determine if they’re looking at something they recognize or something novel. This would be useful in criminal investigations where the murder weapon was kept hidden from the public. If a suspect was read to recognize the item, he could be linked to the crime. Other machines measure pupils sizes to determine arousal which as we have been discussing can signal stress, fear, but also interest. A sniffer machine is also being tested which looks for an increase in stress hormones on the breath.

Such devices are new and their effectiveness unmeasured so are not in widespread use. Thankfully the time we hear “Your plane is boarding, please walk through the mental detector” isn’t yet upon us, and predictions of the popular book 1984 can sit idle, for the time being at least.

Deception Causes Arousal, Generally

by  • March 6, 2013 • 0 Comments

While he COULD be lying, it's much more likely that he's actually anxious. We instinctively (and wrongfully) link anxiety with lying, when in fact good liars often feel no anxiety whatsoever when they lie, and honest people feel anxiety when they think they will be disbelieved.

While he COULD be lying, it’s much more likely that he’s actually anxious. We instinctively (and wrongfully) link anxiety with lying, when in fact good liars often feel no anxiety whatsoever when they lie, and honest people feel anxiety when they think they will be disbelieved.

It is a widely held belief that emotional arousal and stress, is strongly tied with lying. It is also at the heart of the polygraph or lie detector. Here, autonomic responses which happen in our bodies without our conscious control such as sweating or ‘skin conductivity’ is measured as well as increases in heart rate and breathing. It is assumed that when lies occur, stress related behaviours increase. Lie detector machines measure a baseline, that is, they take readings when lying is known to occur and compare it to readings when lying is thought to occur. By reading the differences, lying should become obvious.

We can use similar methods to read arousal without the help of the polygraph. Watching for an increase in adaptors, shifting, subtle movements, touching or scratching the face, neck or nose can show us that someone is uncomfortable. What it won’t show us is the reason for the discomfort. By grilling someone for the truth, this is often enough to cause someone to feel stress thereby creating the behaviour instead of uncovering it. Other clues to an increase in stress includes an increase in eye blinking, changes in posture, avoiding eye contact and foot and leg movement. It is important to always put fear of lying and arousal into context. Someone with little fear, little to gain or loose, or in other words, ‘when the stakes are low’ wont show any of these signals. Aside from this lack of tell, it is important to realize that body language cues, especially lying language is not a result directly of lying, but rather an indication of the stress, fear and anxiety that may or may not be present when lying.