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Small, self-serving lies tend to escalate into bigger ones as time goes by, study finds

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Screenshot of Pinocchio from the trailer for the film "Pinocchio" (1940).

Telling small, self-serving lies may desensitize our brains to the uneasiness usually caused by such falsehoods, thus encouraging us to tell bigger lies in the future, according to a British study published Monday in the journal Nature Neuroscience.

Specifically, the study found that dishonesty gradually increases with repetition and that this escalation is associated with a progressive decline of activity in the amygdala, an area of the brain associated with emotion, including shame and guilt.

This finding offers the first empirical evidence, say its authors, for what happens in the brain “as small acts of dishonesty escalate into larger transgressions” — the pattern often described by politicians, athletes, financiers and others when they “come clean” after being caught in a scandal, whether it’s evading taxes, engaging in sports doping, committing financial fraud or being unfaithful to a spouse.

“When we lie for personal gain, our amygdala produces a negative feeling that limits the extent to which we are prepared to lie,” said Tali Sharot, the study’s lead author and a neuroscientist at University College London, in a released statement. “However, this response fades as we continue to lie, and the more it falls, the bigger our lies become. This may lead to a ‘slippery slope’ where small acts of dishonesty escalate into more significant lies.”

How the study was set up

For the study, Sharot and her colleagues asked 80 adults, aged 18 to 65, to look at 60 high-resolution photos of glass jars containing pennies. They were instructed to estimate (within a range of the U.S. equivalent of about $18 to $42) how much money was in each jar and to then send that estimate via a computer to an unseen “partner” (who, unknown to the study’s participants, was someone involved in the study).

The participants were given different instructions before they sent their estimate to their partner — instructions that offered various incentives to be dishonest.

Sometimes, the participants were told, for example, that the more accurate their estimate, the more money they would share with their partner. Other times, they were advised that by either overestimating or underestimating the amount in the jar, they could receive more money for themselves (at their partner’s expense) or permit their partner to receive more money (at their own expense). 

What the study found

“We observed clear evidence of escalation in self-serving dishonesty, such that the magnitude of dishonesty got larger and larger,” write Sharot and her colleagues. 

Not all the lying was done for the participants’ own enrichment, but “escalation was significantly greater when dishonesty was self-serving than self-harming,” the researchers point out.

To help identify the neural mechanism underlying this phenomenon, the researchers had 25 of the participants undergo functional magnetic resonance imaging (fMRI) while taking part in some of the study’s tasks. These brain scans revealed a sudden jump in activity in the amygdala when the participants lied for their own benefit for the first time. With each subsequent lie, however, the activity in the amygdala declined.

Furthermore, the larger the drop in amygdala activity, the bigger the subsequent lie. 

“It is likely the brain’s blunted response to repeated acts of dishonesty reflects a reduced emotional response to these acts,” said Neil Garrett, a co-author of the study and a post-doctoral researcher at UCL. “This is in line with suggestions that our amygdala signals aversion to acts that we consider wrong or immoral. “


The study was conducted in the rather artificial environment of an academic laboratory. It’s not clear that these findings reflect what happens when people lie in “real world” situations.

Also, there’s considerable controversy about what fMRI scans actually tell us when they “light up” with activity in a particular area of the brain. (One fMRI experiment famously showed that a dead salmon had brain activity.)

Still, the findings are provocative and perhaps help explain why the dishonesty of some serial liars  — including certain very public figures (I’ll let you fill in the blank here) — seems to become bolder and more outrageous as time goes on.

FMI: You can read the study in full on the Nature Neuroscience website.

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Comments (1)

  1. Submitted by Tom Clark on 10/25/2016 - 10:53 am.

    It’s not just the liar

    Those being lied to also come to accept the lie as being normal.

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