The truism that “small lies lead to bigger ones” now has some scientific validation. People placed in a research situation where they could lie repeatedly and be paid more based on the size of their lies increased their dishonesty accordingly. Moreover, the brain adapted to their deceitful behavior.
Researchers showed 80 adult subjects a photo of a jar full of pennies. Each subject was paired with a partner who was in another room and who had a photo that was not clear. The subject was asked to advise the partner on how much money the partner should guess was in the jar.
As 25 of the subjects gave their estimates, an MRI machine scanned their brain. Researchers concentrated on the amygdala, the area of the brain that processes emotional responses, such as shame and guilt.
Major findings of the study follow. When subjects believed that lying about the amount of money was to their benefit, they were more inclined to be dishonest. Over time, the size of their lies increased. Subjects also lied to benefit their partners, but the size of those lies did not increase over time. When subjects initially began lying, there was a lot of activity in the amygdala, but as their lying continued, the response in the amygdala decreased.
Researchers also found that some people don’t lie and don’t increase their lies, but were unable to determine how rare those honest people are. They also found that people lie more when the lie benefits both them and someone else than when the lie benefits them alone.
The research was conducted by neuroscientists at the University College London’s Affective Brain Lab, and published online in the journal Nature Neuroscience.