ABSTRACT
Investigators of social-psychological problems among literate peoples make considerable use of written, as distinct from oral, information. The questionnaire may be regarded as a type of interview which is conducted in writing. Diaries, correspondence, and autobiographies constitute important sources of material for historians. Similar contemporary documents may be useful to psychologists, since they throw light both upon the personality development of the writers, and upon the social groups and institutions which have influenced that development. Patients at mental hospitals are often instructed on admission to write their own life-histories; these are of considerable assistance to the psychiatrist in making his diagnoses. In general, study of the form of questions in questionnaires, verbal tests, and rating scales, of the subject's spontaneous reactions to various types of questions, and of the psychological significance of various types of responses.
