The NY Times has an interesting article this week on the competitive advantage associated with anxiety and people who feel like a fraud. The theory of Evolutionary psychology is one theoretical approach to mental health which attempts to explain a number of psychological issues as the outcome of natural selection, where positive and negative traits are often mixed. In the article, Benedict Carey details how feeling like a fraud can compel you to perform better:

But the dread of being found out is hardly always paralyzing. Two Purdue psychologists, Shamala Kumar and Carolyn M. Jagacinski, gave 135 college students a series of questionnaires, measuring anxiety level, impostor feelings and approach to academic goals. They found that women who scored highly also reported a strong desire to show that they could do better than others. They competed harder.

By contrast, men who scored highly on the impostor scale showed more desire to avoid contests in areas where they felt vulnerable. “The motivation was to avoid doing poorly, looking weak,” Dr. Jagacinski said.

Yet if feelings of phoniness were all bad, it seems unlikely that they would be so familiar to so many emotionally well-adapted people.