Lying is far more common than we’d like to believe and it’s very difficult to know when someone is telling a lie. So it would be useful if a polygraph test were a foolproof means of lie detection. Perhaps that’s why this myth has survived for so long.
Are Lie detectors a Brain Myth? BUSTED! A polygraph test is not an accurate detector of lying.
Lying may be accompanied by feelings of guilt and stress exhibited by physiological symptoms detectable by a polygraph test. But not all people respond the same way to lying. An honest person may be nervous when telling the truth and a liar may not have feelings of stress or anxiety. So it’s very difficult to know the truth.
What a polygraph test is good at detecting
While a polygraph test is NOT very accurate at lie detection, it is very good at detecting physiological state. Since a polygraph machine records bodily signals like sweating, blood pressure, and breathing activity, it offers helpful clues about whether a person is anxious or calm while answering certain questions.
How you feel at any given time – your physiological state – is central to your emotional regulation, behavior, and thinking. Think about it: if you’re late for something important because of traffic and someone cuts you off, don’t you find that you react more strongly than normal? (You’re usually so calm!) Do you find yourself trying to box that person out of a lane? (You’re not usually a vindictive person!) When you’re angry, isn’t it harder to consider the other person’s perspective? (You’re normally very empathetic!)
How is it that we can become so easily hijacked by our state?
It’s actually a favor our body and brain do for us as their first priority is to keep us safe. In service of this and outside of our conscious control, our autonomic nervous system is constantly scanning the physical and social environment for cues of safety and danger.
When the brain/body perceive a threat, an aspect of the autonomic nervous system instantaneously dominates and shifts to support defense rather than health. When this happens, you feel your heart rate increase, your face flush and your palms sweat. Your breathing increases and your body prepares to fight or flee. In this situation, you have no time to think things through rationally and no capacity to be social.
When the brain/body appraise the environment as safe, defensive responses are inhibited and a calm state emerges. Your heart rate slows, your muscles relax and your breathing becomes more regulated. You can see this in your face and hear it in your voice – both have expression. When you feel this way, you can rest, digest, control your emotions and thinking, learn, and you can be social.
It’s a benefit to be able to shift flexibly between these responses. Once a threat is gone, it’s important to be able to return to a calm state for your health, and your ability to learn and be social. With this ability comes resilience, greater emotional bandwidth and balance. For many though, their risk detection system is biased toward detecting danger when there is no real danger. People with autism, schizophrenia, anxiety, depression, and attachment disorders are particularly at risk for this.
What is true
Our physiological state affects everything we do. So what we need more than anything is to have better state control. It makes the difference between surviving life and living life. Honestly.