Friends recommended this episode of "Radio Lab," I think because it tells the story of a rabid sociopath/narcissist con artist (not clear which). There was also some really interesting information about what the brain of a liar looks like:
Yang and her colleagues put all 49 people, both the liars and the non-liars, into a magnetic resonance imaging scanner and took pictures of their prefrontal cortex. They chose to focus on this area of the brain because previous studies had shown that the prefrontal cortex plays a role in both lying and in antisocial behaviors.
If you could look into this part of the brain, which sits right behind your forehead, you would see two kinds of matter: gray and white. Gray matter is the groups of brain cells that process information. Most neuroscience studies focus on gray matter. But nearly half the brain is composed of connective tissues that carry electrical signals from one group of neurons to another. This is white matter. Roughly, gray matter is where the processing happens, and white matter connects different parts of the brain, helping us to bring different ideas together.
The liars in Yang's study had on average 22 percent to 26 percent more white matter in their prefrontal cortex than both the normal and antisocial controls.
Yang speculates that the increase in white matter means that people who lie repeatedly and compulsively are better at making connections between thoughts that aren't connected in reality — like, say, "me" and "fighter pilot." Consequently, while some of us struggle to come up with reasons why we were late for work, or can't go out with someone we don't really like, Yang's liars impulsively serve up a heaping helping of excuses and stories, and fast.
"By having more connections," Yang says, "you can jump from one idea to another and you can come up with more random stories and ideas."
Admittedly, this study is just a first step. It doesn't show that more white matter in the prefrontal cortex accounts for all lying or that it's the only part of the brain involved. And the study does not establish whether the brain differences lead to lying or whether repeated lying somehow "exercises" connections in the brain. While the study was carefully designed to exclude differences that could be due to age, ethnicity, IQ, brain injury or substance abuse, the small sample size means the results need to be replicated. More research is needed to define what behaviors count as pathological lying and to establish the mechanism behind those behaviors.