Almost everyone lies occasionally, but for a small percentage of people, lying isn't something that they do every once in a while -- it's a way of life. Drew Curtis, PhD, of Angelo State University, and Christian L. Hart, PhD, of Texas Woman’s University, authors of a new book on pathological lying, talk about what drives “big liars” to lie, why they believe pathological lying should be classified as a mental health disorder, whether liars really are more prevalent in some professions, such as politics and sales, and how you can recognize lies and protect yourself from being duped.