Dr. Hervey Cleckley, an American psychiatrist distilled what he believed to be 16 key behavioral characteristics that defined psychopathy. Most of these factors are still used today to diagnose sociopaths/psychopaths and others with antisocial disorders. Here are some of those behaviors:
1. Superficial charm and good intelligence.
2. Absence of delusions and other signs of irrational thinking.
3. Absence of nervousness or neurotic manifestations.
5. In truthfulness and insincerity.
6. Lack of remorse and shame.
7. Pathological egocentricity and incapacity for love.
8. Specific loss of insight.
9. Suicide threats rarely carried out.
10. Sex life impersonal, trivial, and poorly integrated.
Source: Psychology Today