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.