Robert D. Hare, Ph.D., is considered one of the world's foremost experts in the area of psychopathy and he is the author of the popular book Without Conscience.

Dr. Hare is a professor of psychology at the University of British Columbia, and has researched psychopathy for more than twenty years. The following is his well-known and implemented psychopathy checklist.

For each characteristic that is listed, the subject is given a score: 0 for "no," 1 for "somewhat," and 2 for "definitely does apply." (Please note that Dr. Hare does not advise that the layman use this checklist for "diagnosing" friends and family; this checklist, however, does give you a good idea how it is used).

1. Glibness/superficial charm
2. Grandiose sense of self-worth
3. Need for stimulation/proneness to boredom
4. Pathological lying
5. Conning/manipulative
6. Lack of remorse or guilt
7. Shallow affect
8. Callous/lack of empathy
9. Parasitic lifestyle
10. Poor behavioural controls
11. Promiscuous sexual behaviour
12. Early behaviour problems
13. Lack of realistic, long-term plans
14. Impulsivity
15. Irresponsibility
16. Failure to accept responsibility for own actions
17. Many short-term relationships
18. Juvenile delinquency
19. Revocation of conditional release
20. Criminal versatility
Narcissism is also a characteristic