Can You Beat a Lie Detector
The internet is full of tips on how to “pass a polygraph”. Most of them are about the classic device with sensors and about the 1990s. Let us go through them one by one and see what still works. In short: these tricks are designed for the classic polygraph, not for a test based on eye movements.
Tips from the internet and what is wrong with them
All the known countermeasures are designed for the classic polygraph: it measures breathing, blood pressure and sweating, and these can be changed deliberately.
- A tack in the shoe, tensing muscles: creates an artificial reaction to control questions. An experienced polygraph examiner sees it on the chart, and EyeDetect does not measure the body at all.
- Sedatives or alcohol: blunt reactions evenly, and the test is declared invalid. On EyeDetect, a person under the influence is not admitted to the test.
- Counting in your head, recalling something unpleasant: aimed at the polygraph, because it changes breathing and blood pressure. Mental effort does dilate the pupil too, but EyeDetect does not assess a single reaction: it compares types of statements together with response times and errors.
- “Believing your own lie”: sounds good, but the brain still spends more effort on a false answer. That effort is exactly what is recorded.
Why the eyes do not lie
The pupil dilates by fractions of a millimeter when the brain works harder. This cannot be controlled consciously, just as you cannot order your heart to stop beating. EyeDetect also records reading speed, re-reading of words, response time and errors. The algorithm weighs dozens of such measures, and the person controls none of them.
There is one more detail. The statements on the screen are repeated many times in different wordings. You can lie once; lying consistently 60 times in a row is much harder.
What happens if you try
The algorithm has a separate category, “random responding”: when a person presses the buttons at random, stalls for time or does not read the text. Such a test is declared invalid and does not look “truthful”. For the client, that is information too.
What really affects the result
Not tricks, but condition: lack of sleep, severe anxiety, poorly worded questions. That is why before the test we explain every question, give a practice test and ask you to get a good night's sleep. An inconclusive result most often comes from fatigue or nervousness. In that case we run a retest at our expense.