How the brain reveals if someone is lying

Aug 31, 2022 | News & Science

Lie detector tests are on the rise. When someone is lying, the gnawing doubt is unbearable- you need to know the truth.
The problem with lying is that it destroys trust, leaving you unable to believe anything someone tells you. How can you tell if someone is lying? According to the 42 percent of marriages end in divorce.

The second most common reason after money problems (which can also involve lying), is betrayal leading to ‘difficulties in establishing honesty in a relationship’.

Dishonesty in a relationship can affect every area of your life; from drugs, to theft, paternity, recruitment, insurance claims and abuse, lying can cause significant damage to the many different types of relationships that we build throughout our lives.
According to, lying causes so much destruction because ‘the level of our faith is shattered and the next time we find it harder to trust’.

Worse still, ‘it is a deliberate choice to fabricate the truth….. lies can also build on themselves, leading to bigger lies’….. and ‘a false sense of reality…after repeatedly lying about the same thing, we may even come to believe that it is true’. Thus, the impact on the recipient of the lies can be huge.

We often have some sort of gut instinct that something isn’t right when we are being lied to, but until you have proof, there is no way to be sure. As a result, doubt and mistrust can linger on in relationships for years, decades even, causing bitterness, resentment and wider relationship breakdown as others get involved.

Can you test if someone is lying?

People rarely admit that they are lying. Filled with a sense of foreboding and a deep nagging doubt, it gets to the point where you need to know the truth, one way or another.

Thus, throughout the ages, humans have developed lie detector tests to find evidence to prove whether their instincts were right.
Witnesses have always been an option, in some situations. In the early days of lie detection, witnesses could be called to shred some light on the matter in hand, however this was merely one person’s word against the other, so there was still a need to have concrete evidence. And lie detection evolved. It was an Ancient Greek physician, Erasistratus, who first used signs from the body to uncover deception, when ‘Antiochus’ pulse, and its tumultuous rhythm’ betrayed his love for his step-mother.

From then on, lie-detector tests have used subtle, innate signals from the body to uncover lying. From a red-hot poker on the tongue or in the hand, to swallowing dry bread or rice or sniffing out dishonesty through smell.3 Humans throughout history have found that the body cannot lie. If you want to detect if someone is lying- the body will let you know.
Today, thankfully, we have moved on from burns and choking, to hard, scientific, factual evidence that can be gained from neuroscience.

What is neuroscience?

Neuroscientists study how our nervous system works. Our nervous system is the important, intricate network in our body made up of our brain, spinal cords and nerves.
The nervous system is a matrix of electrical and chemical signals, creating the perfect environment for scientific evidence-gathering.

How your brain will reveal if someone is lying?

Behaviour kicks our nervous system into action. Any of our responses, produce chemical and electrical signals as the nervous circuit gets to work. Moving around our body, the signals can show us how our brain, and other parts of our body, react to all sorts of different emotions and responses, including lying.
When you lie, the brain has to work overtime. Therefore, an honest brain and a dishonest brain will show different levels of activity, when monitored.
The area of the brain responsible for language has to both respond and construct a plausible lie at the same time, hence the reason that to the recipient, a lie never fully makes sense. Additionally, the person lying is now in danger of letting their dishonesty slip.
Therefore, now, the body is both responding and preparing for likely danger. So the amygdala, ACC (anterior angulate cortex), as well as the thalamus and the caudate have to all get to work to prepare lots of different parts of the body for imminent danger.
We have all seen this in action. The person lying, focused on the lie, thinks they look normal, the listener however, can hear and see abnormalities – so too can science.

When someone is lying, scientists can measure the heightened activity in the brain and there are other tell-tale chemical signs going off around the body, at the same time too.

What the body does when someone is lying

The amygdala is our superior body guard. Unstoppable once released, it is our alarm system to prepare our body to either run or fight an incoming threat. Therefore when someone is lying, although they think their panic is hidden- the amygdala will show their true colours.

Releasing adrenaline into the body, a person who is lying will display:

– Increased heart-rate
– tensing of the muscles
– a change in breathing pattern
– heightened awareness
– vasoconstriction

and many other internal changes such as the release of glucose, the removal of blood from vital organs to protect the brain and mood swings as the fight mechanism causes angry responses, followed later by a return to calm as the chemicals subside.
A stunning, efficient system that cannot be tampered with, neuroscience means that we no longer have to call witnesses or physically hurt people to finally find out the truth when we suspect someone is lying.

Today we have polygraph tests – also known as lie detector tests – the modern, evidence-based way to finally prove whether someone is lying or not. Used widely across the world, from the U.K. to America, polygraph tests can provide a way for private, business and government services to release that nagging doubt and begin to mend relationships.
Whether you are experiencing problems with dishonesty in: infidelity, paternity, recruitment, insurance claims, fraud or theft, we can provide a quick and simple solution, to bring an end to the issue, once and for all.

Our experienced and qualified staff, work with empathy and care to help you resolve any issue. Speak to one of our friendly team today.

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