Children with good "executive function" skills, including self-control and the ability to focus on tasks, tend to be more skillful liars, Dr. Talwar says.

WSJ: How to Handle Little Liars

In an as yet unpublished study, Dr. Black and colleagues found that 26 compulsive shoppers had similar executive function (the ability to plan, organize, reason and anticipate consequences) as 32 control subjects.

WSJ: Shop 'Til You Stop: How to Treat Compulsive Spending