Small Lies, Big Habit: How the Brain Adapts to Lying
Lying is a vicious cycle. Not only does one small lie often lead to another, but over time, the liar’s brain adapts to dishonesty and stops generating emotional responses to it. Science journalist Simon J. Makin discussed recent research and discoveries in this area in Scientific American.
Liar, Liar: How the Brain Gets Used to Telling Tall Tales
As seen in past U.S. presidential campaigns, the more a person lies, the easier it seems to become. But politics isn’t the only field full of dishonesty. In 1996, Bernard Bradstreet, co-executive director of Kurzweil Applied Intelligence, was sentenced to prison for fraud. His initial offenses were relatively minor—he reported sales in quarterly reports that hadn’t actually closed yet. But things escalated: Bradstreet began inflating sales figures by millions of dollars, making the company appear profitable and attractive to investors, even though it was actually losing money. Similar stories surfaced after the Enron scandal, one of the largest bankruptcy cases in U.S. history.
Such cases, where a small lie snowballs into major dishonesty, are common. That’s why a team of researchers from University College London (UCL) and Duke University decided to study the phenomenon. As senior author and neuroscientist Tali Sharot notes:
“Whether it’s tax evasion, infidelity, doping in sports, data manipulation, or financial fraud, deceivers often recall how a small lie gradually snowballed over time.”
The team’s results, published in Nature Neuroscience, confirm in laboratory settings that with each repetition, lying becomes easier. The researchers also used brain scans to identify the neural mechanism that may explain why this happens.
“We suspected there must be a basic biological principle in the brain’s response to lying that leads to emotional adaptation,” says Sharot.
How the Experiment Worked
The study involved 80 adults. Each participant was shown large images of glass jars filled with coins (each containing between £15 and £35) for three seconds. They were told to estimate the amount of money in the jar for a partner (played by actors), who only saw a small image of the same jar for one second. Participants knew their advice was supposed to help their partner estimate the amount. This allowed researchers to observe how participants evaluated the jars when they had no reason to lie.
Later, participants were given other tasks, some of which encouraged lying. Comparing “honest” and “dishonest” estimates allowed the team to measure behavioral differences.
Depending on the scenario, dishonest behavior could benefit the participant at the partner’s expense, benefit the partner at the participant’s expense, benefit both, or benefit just one without affecting the other. For example, in one scenario, participants were told they would be rewarded based on how much their partner overestimated the amount, while the partner would be rewarded for accuracy. Participants were also told that the partner was unaware of these new instructions.
Findings: When and Why People Lie More
The researchers found that when participants had selfish motives, dishonesty occurred in at least 60 interactions between participants and partners. Participants also lied to benefit their partner, but the frequency of these lies remained stable throughout the experiment. When both parties benefited, participants lied even more, suggesting this type of dishonesty felt more acceptable.
“People lie the most when it benefits both themselves and someone else,” Sharot notes. “When it only benefits them but harms someone else, they lie less.”
However, over time, the number of lies increased when the participant personally benefited. Apparently, self-interest is a key factor in escalating dishonesty.
“This study is the first empirical evidence that dishonest behavior becomes a habit as it is repeated, even when all other conditions remain constant,” lead author Neil Garrett, a cognitive neuroscientist at UCL, told reporters.
What Happens in the Brain When We Lie
Twenty-five participants performed the task while undergoing functional MRI scans, allowing researchers to measure brain activity. The scientists focused on brain regions known to respond to emotional stimuli, especially the amygdala, which is responsible for emotional responses and the formation of emotions. Activity in this area was initially high when participants lied, but decreased with each new act of dishonesty.
Importantly, the greater the decrease in activity in this region, the more likely participants were to tell bigger lies. This suggests a biological mechanism underlying the escalation of dishonesty. The phenomenon, called adaptation, leads to reduced neural responses to repeated stimuli. For example, emotional activation of the amygdala in response to unpleasant images decreases after repeated exposure. A similar process may be at work here.
“When we first lie, for example about our income, we feel bad about it. That’s good, because such feelings restrain our dishonesty,” Sharot explains. “The next time we lie, we’re already adapted to the situation. The negative reaction that could hold us back is reduced, and we’re able to lie even more.”
Implications and Further Research
Some researchers note that these findings need to be confirmed by further studies.
“It’s an intriguing hypothesis that the adapted amygdala response may underlie the escalation of self-serving dishonesty,” says neuroscientist Tom Johnston of the University of Reading, who was not involved in the study. “But the results should be replicated with a larger sample to study the involvement of other brain regions that also play a role in forming and regulating emotional responses.”
Sharot’s team suggests the results may also apply to other behaviors. “This same mechanism may underlie other types of escalation, such as increased risk-taking or aggressive behavior,” Garrett notes, adding that the study “highlights the potential dangers of engaging in small acts of dishonesty, which can become habitual over time.”