Psychoanalytic theory suggests that criminality may be reflective of a weak, defective, or incomplete superego. Kohlberg's theory of moral development suggests that the preconventional level of functioning, in which rules and social expectations are viewed as external to the self, is characteristic of children under 11 years old and of some delinquents and adult offenders. Eysenck's personality theory posits that extroverted, impulsive, and aggressive individuals are more prone to criminal behavior. Social learning theory suggests that aggressive behaviors can be learned from the family, from social models or peers, or through symbolic modeling. Operant conditioning theory suggests that behaviors can be learned through positive or negative reinforcement. In addition to providing an account of the acquisition of criminal behavior, this theory has also been used in developing behavior modification programs for delinquents. Finally, a number of theories equate criminality with mental illness or antisocial personality. 5 annotated references.