Bullies have little egos: Aggressive criminals typically think more highly of themselves than most people do. Violence in response to a challenge is not necessarily protecting a fragile ego, but a defense of their positive self-perception.

Narcissism is necessary for success: It is often thought that self-confidence and self-centeredness are required to be successful. Truth is, narcissists are actually less successful because of their tendencies to set unrealistic goals, take too many risks and alienate others.

Obesity is a genetic problem: "Fat genes" mean that a person has slow metabolism, or so conventional wisdom goes. Research suggests genes cause obesity mostly by influencing eating behavior.

Trauma requires counseling: There is some evidence to suggest that encouraging people to talk about a recent trauma or visualizing it might actually contribute to posttraumatic stress disorder, not prevent it.

Unqualified praise is good: Telling kids that everything that they do is wonderful, no matter what, is not a good idea. This does not create a relationship between behavior and consequences and the sense of achievement that comes from accomplishing something difficult. Taking on a challenge and succeeding gives children more of sense of earned merit that unconditional praise.

You know yourself best: We would like to think this. Several studies, however, have demonstrated that friends could predict people’s behavior as well as, and in some cases better, than those people could predict their own behavior.

Therapy is a long process: Studies of brief and solution-focused therapies can be effective after only a few sessions. Even long term therapy approaches are most effective in the first few months.

Subliminal ads work: The belief that subliminal advertising can influence us to buy products we wouldn’t otherwise buy is fairly pervasive. The claims simply have no foundation in science. This belief can be traced to a 1950s study that was completely fictional!