This book concentrates on the study of psychopathic disorder as defined in the 1959 Mental Health Act in Great Britain. This definition reads as follows: "A persistent disorder or disability of mind (whether or not including subnormality of intelligence) which results in abnormally or seriously irresponsible conduct on the part of the patient, and requires or is susceptible to medical treatment."
The subjects who provided the material for the observations and studies reported on are 100 consecutive admissions and one later admission to Balderton Hospital, a state hospital near Nottingham in the Midlands. The criteria for their selection were that they had an IQ over 60, were over 13 years of age, that they were deemed in need of psychiatric hospital admission, and were not neurotic or psychotic. They had to have demonstrated antisocial behavior as evidenced by prior convictions for the large majority of