Researchers Reveal Why Liars Keep Lying


Behaviorally, we show that the extent to which participants engage in self-serving dishonestly increases with repetition. Using functional MRI, we show that signal reduction in the amygdala is sensitive to the history of dishonest behavior, consistent with adaptation. – Garrett, N. et. al, “The brain adapts to dishonesty”

The intentional telling of untruths, commonly referred to as ‘lying,’ is something that most people – if not all people – are guilty of. Dishonesty is an inherent part of life in society, and adversely influences a number of arenas – both large and small; both individually and collectively. We can all pretty much agree on these points.

Something that we’re all likely in agreement on: some people lie more than others. In some cases, much more than others. Perhaps we’ve all known or been acquainted with someone with a propensity for telling untruths. Such individuals are often called ‘compulsive liars,” as their ability to manipulate the truth seems to have to boundaries.

This Is Why Liars Keep Lying

Why do liars keep on lying? Even in cases where they fully comprehend the pain that lying inflicts, why do people compulsively engage in dishonesty? Is it a choice? Is there something wrong with their brain?

To shine some light on the complex matter of compulsive lying, a team of researchers at University College London (UCL) engineered a fascinating experiment.

The Study

The rationale given for the study, published in the journal Nature Neuroscience:

From financial fraud to plagiarism, online scams and scientific misconduct, deceivers retrospectively describe how minor dishonest decisions snowballed into significant ones over time. Despite the dramatic impact of these acts on economics, policy and education, we do not have a clear understanding of how and why small transgressions may gradually lead to larger ones.

In simple terms: the team wanted to know why lying not only appears to increase frequency, but in scope.

The researchers decided to recruit 80 participants and monitor their brain activity using a Functional magnetic resonance imaging (fMRI) machine. However, the team recognized the inherent difficulty in observing deception using brain scans, as “participants need to repeatedly, deliberately and voluntarily act dishonestly in a social context without being required to admit their dishonesty.”

To work around these difficulties, the team devised a creative experimental model, whereby they were able to observe and quantify deception using a trial-by-trial method. Specifically, the team created a two-party experiment.

Each person advised their “partner” on the amount of money contained in a glass jar with pennies. Importantly, there were incentives involved which served as the motivation to deceive. Over the course of the experiments, the incentive model was altered, so that the money would benefit or harm one of the two partners. In every case, the participant was required to lie in order to benefit themself. 

Total, the team conducted two experiments:

Experiment #1: Both the participant and partner benefit if participant lies; only participant benefits if they lie; or partner benefits.

Experiment #2: Either the participant or partner benefits, excluding either/or if the participant lies.

Experiment Results

We observed clear evidence of escalation in self-serving dishonestly (participant only benefits), such that the magnitude of dishonesty got larger and larger…

The ‘magnitude’ of dishonesty escalated with self-serving incentives, as opposed to self-harming (partner benefits, affecting the participant). In other words, the majority of the 80 people were much more likely to lie when the circumstances benefitted only themselves, while completely disregarding their partner’s stake.

The team’s hypotheses, then, were proven correct by this study. In each trial, the instances of dishonest behavior quantitatively increased. Per the study:

If indeed signals that may help curb dishonesty diminished over time, dishonest acts could increase. Thus, what begins as small deviations from a moral code could escalate to large deviations with potentially harmful consequences.

The ‘signals’ the researchers are referring to is the activity of the brain known as the amygdala. Arousal of the amygdala is a response to “various emotion-eliciting situations, with stronger activity related to more potent experiences.”

Related article: 5 Phrases Liars Use To Make You Believe Them

Myriad research studies have confirmed the central role of the amygdala in experiencing emotions. Lying and dishonesty, to most people, is an uncomfortable act. Hence, our amygdala responds accordingly by activating to the stimulus.

It Also Explains Why Liars Keep Lying

As the researchers observed the fMRI scans, it was clear that dishonest behavior such as lying increases activity of the amygdala. Furthermore, the team observed with each subsequent experiment – as the participants continued to lie – the less active the amygdala became.

In other words, when dishonesty and lying become habitual, the part of the human brain responsible for emotional arousal – not to mention, self-control – simply accepts such activity as normal. It is anything but…

Garrett, N., Lazzaro, S. C., Ariely, D., & Sharot, T. (2016, October 24). The brain adapts to dishonesty. Nature Neuroscience, 19(12), 1727-1732. doi:10.1038/nn.4426
Park, A. (2016, October 24). The Fascinating Reason Why Liars Keep On Lying. Retrieved December 02, 2016, from
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