We´re standing in the line to get into the amusement park when we see a sign that says “children up to 12 years old, reduced ticket”. Suddenly our teenage son, who has just turned fourteen and has a bigger mustache than Super Mario Bros, turns out to be twelve. We walk a couple of meters and we are facing a sign that indicates unambiguously that we cannot take food or drink onto the premises. However, our backpacks contain enough sandwiches, chips and soft drinks to set up an improvised grocery store. We act dumb.

Once on the premises we meet a former co-worker. Faced with the usual “Man! How are you? How´s things? “, we reply,” Very well! The truth is that I can´t complain “. Really? The night before, we hardly slept because of the tension and back ache generated by the decision to quit our job and, to top it all, the dog is sick. But we are “Very well!”. Half an hour later, while our “Super Mario” stands in line to get on the Tornado, our mobile phone rings. Quickly the screen informs us that a new work mail has arrived in the inbox ready to sour our day with the subject “URGENT”. We decide to ignore it: “Sure, man! … I’m on vacation!”. When our boss calls us on the telephone the next day we answer in surprise: “Mail? What mail? I have´nt received any mail. ”

Can you imagine what life would be like for a person, a society or a planet that lies every 3 minutes? This article picks up a few brushstrokes of research that I have carried out in recent months. Does living life dishonestly influence our body? What effects does a dishonest act have on a neurological and biological level? Is it possible to change our way of acting from a neurobiological point of view? Let’s get started.

We humans lie

Scraping around in the trunk of scientific studies we find a good handful of them that try to establish the role of lying in people´s daily lives . To get an idea of where things are going we will select two of them. Virginia University researcher Bella DePaulo conducted an experiment that concluded with interesting facts: in any given week we lie to 35% of the people with whom we have a conversation. In the case of the work of Robert S. Feldman of the University of Massachusetts the data revealed that we usually lie once every 3 minutes on average.


Leaving numbers aside, honesty is a scarce commodity. Researchers agree that we read less than we presume, flirt more than we admit, exaggerate comments that hurt us, buy things more expensively than we recognize, smoke more than we admit or do less exercise than we proclaim. Lying is part of our lives to such an extent that we see deception as a crucial mechanism for the proper functioning of our society, developing algorithms capable of detecting lies by analyzing the syntax of sentences (as in the case of Dr. Ludwig and his team). In a short time, it will be possible to use these lie-hunting algorithms with the same ease as the spell checker in Word or our mail manager.

The Honest Brain: From Lie to Honesty

Neuroimaging allows us to see what happens inside a person’s brain when he or she performs a specific activity (for example, when deceiving or lying) without having to slice your skull open. Functional MRI is a way to get in, take a look at brain activity (specifically the blood oxygen levels that consume neurons) and tiptoe out. Business as usual! Although we know that not all people use the same brain areas to perform the same action, it is common to generalize.

Let’s put on our white coat and head into America´s Virginia Tech Carilion Research Institute to find out which brain area is crucial to honesty. At its facilities, a group of scientists has studied the brain of 7 patients with lesions in the prefrontal cortex with the aid of a functional magnetic resonance device, and have concluded that this region plays a fundamental role in honesty. To understand where we are, the prefrontal cortex corresponds to the area that you would cover with your hand if you put it on your forehead. Well, that´s the first step successfully taken: it seems that we have “located” honesty.



Now let’s rent a car and drive to the state of Pennsylvania to visit its university. After asking in reception for Dr. Langleben, we arrive at the radiology and psychiatry department of the University of Pennsylvania. Among the experiments carried out by the research group, we will focus on a study carried out in 2002 which revealed something incredible: before the lie is communicated to other people an alarm is triggered in an area of the prefrontal cortex known as anterior cingulate cortex.

Here we find a paradox. We all think that a lie is forged when it is expressed to others and that it will never exist if we do not communicate it to other people. Contrary to this idea, the work done in the laboratories indicates that for our organism the rules are different: it does not matter if it is communicated or not. The human brain has an “honesty detector” located in the anterior cingulate cortex that responds not to whether we lie, or tell the truth to the people around us, but to the simple fact of being honest or not.

Biología y fisiología de la honestidad

We have discovered that thinking of something dishonest sets off our honesty detector. The next step would be to determine what biological and physiological processes our detector impulses when the alarms go off. Honesty behaves like a catalyst that makes the body adopt a characteristic chemical composition at full speed. We spoke earlier about how this process takes place, how a dishonest thought can turn into a chemical change and wander around in our blood, in the article “We feel what we think.”

To meet the stars of the show we only have to analyze a sample of saliva or blood of a person who is being dishonest; the lights turn on in reaction to cortisol and testosterone. These hormones behave like messenger pigeons that boost different physiological processes that we can measure. Cortisol is known as the “stress hormone,” and finding elevated blood levels is associated with increased pressure in the arteries, acceleration of the heart, agitated breathing or dilation of the pupils. The other co-protagonist, testosterone, is the “male hormone” par excellence (although women also produce it in lesser quantity), and its function is to reduce, among other things, our empathy with the world.

Now, nobody get apocalyptic. Our body comes with the built-in necessary tools to undo a dishonest act and restore the normal functioning of the body. Once the dishonest episode is over, everything returns to normal unless we string one dishonest act after another, since cortisol and testosterone would remain permanently on the playing field. Elevated levels of these “chronic” hormones make us firm candidates for thyroid disorders (a butterfly-shaped gland that we have in our neck, and influences the chemical reactions that occur in our body), inflammatory disorders, diabetes or high blood pressure.

¿Es contagioso el engaño?


A lie that remains in our mind, whether or not projected to the outside, affects us just as Dr. Langleben and his colleagues discovered. That said, when we share it and make it real, it intensifies in our organism and infects the people around us. Just as a person sitting by our side while lighting a cigarette is a passive smoker, an observer who witnesses how we steal or cheat is a passive “victim” of our dishonesty. Ten Brinde and his team of collaborators demonstrated that the organism of the observer behaves as if he himself was committing the dishonest act, affecting parameters such as the electrical activity of the skin and the functioning of the cardiovascular system among others. This mechanism can be explained by the operation of mirror neurons (the empathy motor in mammals) which we will speak about in due course.

Turning the tables, we discover something more than interesting: we not only transmit the dishonest act, but also the acts of honesty. When we witness honest actions, our levels of cortisol and testosterone in blood decrease, whilst establishing a link with the originator.


Translate by Philip Barnes



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