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.
More ConnectionsYang 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."