ABSTRACT
ACRIMINAL scientist is seldom able to observe the activities which form the theoretical focus of his work. This is a handicap which bears more heavily upon the psychologist than upon his sociologist colleagues, for the social environment which is their primary concern has a certain degree of permanence. The values and standards of an offender's social group do not change overnight, although his status within it may do so. But the particular sequence of behaviour and experiences in which the psychologist is interested has usually occurred long before he has any knowledge of it, and is often witnessed by none but the criminal himself.
