Each Time You Lie, Your Brain Becomes More Desensitized to Lying

The brain is a malleable machine—even when it comes to lying. A team of scientists has concluded that your brain adapts itself to dishonesty.

Specifically, the act of telling a self-serving lie (no matter how small) paves the way for bigger falsehoods. The study, which seems to corroborate the “slippery slope” narrative described by politicians, public figures—even our own partners—when they engage in wrongdoing, was recently published in the journal Nature Neuroscience.

“Behaviorally, we show that the extent to which participants engage in self-serving dishonesty increases with repetition,” the scientists wrote in the study’s abstract. They noted that activity in the amygdala, a part of the brain that deals with emotion, decreases with each subsequent lie. In addition, the extent of that decrease predicted the enormity of the next lie.

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It’s not just the nose. If Pinocchio were real, his amygdala probably became less active each time he lied.

Here’s Erica Goode, reporting for The New York Times:

Participants in the study were asked to advise a partner in another room about how many pennies were in a jar. When the subjects believed that lying about the amount of money was to their benefit, they were more inclined to dishonesty and their lies escalated over time. As lying increased, the response in the amygdala decreased. And the size of the decline from one trial to another predicted how much bigger a subject’s next lie would be.

These findings suggested that the negative emotional signals initially associated with lying decrease as the brain becomes desensitized, Dr. Sharot said.

“Think about it like perfume,” she said. “You buy a new perfume, and it smells strongly. A few days later, it smells less. And a month later, you don’t smell it at all.”

The team isn’t sure what causes this decrease in signal—whether it’s the negative emotions associated with lying or something else. But parts of the experiment have been replicated, and the researchers are certain that the signal reduction is related to the act of lying.

That in itself in a major accomplishment. Dishonesty is a difficult phenomenon to study, likely in part because complex emotions are involved. The researchers say that wherever this finding takes them, the emotional component of lying will be a key factor in future work.