Everybody lies at some point, but scientists say they've uncovered a biological mechanism supporting the "slippery slope" that leads some from smaller acts of dishonesty to larger transgressions. Reporting in the journal Nature Neuroscience, they write that MRI scans allowed them to watch how a particular part of the brain—the amygdala, where emotions are processed—changed when lies were told. The upshot? "The brain adapts to dishonesty." Study author Tali Sharot tells the New York Times that it's similar to how one adapts to the smell of perfume: "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."
To test this, researchers presented 55 participants with pictures of jars full of pennies and asked them to tell a partner how much money was contained in the jar. Over dozens of short experiments, the participants were incentivized to lie to varying degrees for varying outcomes. Generally, the amygdala showed the most change when the first lie was told, but the change decreased as the lies grew. Essentially, people became desensitized to lying, some more than others. Someone who'd repeatedly lie for a few pennies was more likely to lie for more money later, reports NPR. Sharot says follow-up work should examine whether this kind of adaptation escalates other behaviors, such as violence. (See where the US ranks when it comes to deception.)