Nor is this choice necessarily an unreasonable one. As the Court notes, “[ejvidence of a difficult family history and of emotional disturbance is typically introduced by defendants in mitigation.”
Ante, at 115. One might even be surprised if a person capable of a brutal and unprovoked killing of a police officer did not suffer from some sort of “personality disorder.” Indeed, Dr. Dietsche, who testified that Eddings had a “sociopathic or antisocial personality,” see
ante, at 107, estimated that 91% “of your criminal element” would test as sociopathic or antisocial. App. 136. Dr. Dietsche defined “antisocial personalities” as individuals without “the usual type of companions” or “loyalties,” who are “[f]requently . . . selfish, . . . very impulsive,” showing “little in the line of responsibility” or concern “for the needs or wants of others,” and “hav[ing] little in the line of guilt or *127remorse.”
Id., at 137-138. Although the Court describes Dietsche’s testimony as indicating that “approximately 30% of youths suffering from such a disorder grew out of it as they aged,”
ante, at 107, Dietsche was in fact describing a study which he thought had subsequently been discredited. App. 139-141. Even that study, however, concluded that most of those who “grew out of” the disorder by the age of 35 or 40 were “more of a con-artist type” and “not. . . the assaultive type.”
Ibid. A more recent study estimated that only 20% of sociopathic persons were “treatable,”
id., at 141; in this study, only 9 of 255 initial participants were successfully treated, after “literally . . . thousands of hours of therapy.”
Id., at 142. Thus, characterization of Eddings as a “sociopath” may connote little more than that he is egocentric, concerned only with his own desires and unremorseful, has a propensity for criminal conduct, and is unlikely to respond well to conventional psychiatric treatment — hardly significant “mitigating” factors. See
Blocker v.
United States, 110 U. S. App. D. C. 41, 48-49, and nn. 11, 12, 288 F. 2d 853, 860-861, and nn. 11, 12 (1961) (Burger, J., concurring in result). While the Court speaks of Eddings’ “severe emotional disturbance,”
ante, at 115; see also
ante, at 116, it appears to be referring primarily to the testimony that Eddings was a sociopath, and to Dr. Gagliano’s rather fantastic speculation concerning Eddings’ dissociation at the time of the crime, see n. 4,
supra. The Court’s opinion exemplifies the proposition that the very occurrence of the crime functions as a powerful impetus to search for a theory to explain it. See Szasz, Psychiatry, Ethics, and the Criminal Law, 58 Colum. L. Rev. 183, 190-191 (1958).