Childhood: W. Norwood East. Delinquency and Mental Defect (I). British Journal of Medical Psychology, 1923, Vol. III, p. 153.

In this paper East discusses certain criminal actions associated with mental deficiency. In dealing with criminals, individual consideration is essential. The number of mental inefficients among the prison population is estimated at about 5 per cent. In prison work the diagnosis of mental defect may be extremely difficult. Although the nature of the offence forming the actual charge may have no diagnostic value, the method and circumstances with which it is associated are frequently important. It is probable that in defective delinquents, acts of dishonesty are liable to appear at an earlier age than other criminal actions. Two classes of mental alienation are recognized in criminal law: Dementia accidentalis and Dementia naturalis or absence of understanding from birth. Difficulties in diagnosis due to malingering may be due to the ordinary criminal assuming mental defect or to the mental defective assuming normality. In prison work the most difficult cases to diagnose are those of a mixed mental deficiency and insanity. In these combined cases the defect does not affect the responsibility of the accused, whereas the insanity may. In working out the mental age of a patient by intelligence tests the author finds that if there is an abrupt ending to correct answers, at say 9 years, one is probably dealing with defect, also if for a year or two after, an occasional test is answered satisfactorily, it is defect, but if the occasional correct answer extends to the late years of the test series, acquired mental disorder or malingering is suggested. In the author's experience moral imbecility is rarely met with in prison, the diagnosis being more difficult than in any other form of mental deficiency. In the differential diagnosis between the habitual criminal and the moral imbecile it is of fundamental importance to recognize that the moral imbecile does not take elaborate precautions to hide his crime or avoid punishment. The paper is illustrated by some ve