General: Walter Hollitscher. 'ber die Beziehungen zwischen der psycho-analytischen und behaviouristischen Begriffsbildung.' ('The Relation between the Nature of Psycho-Analytical and Behaviouristic Concepts.') Internationale Zeitschrift für Psychoanalyse und Imago, 1939, Bd. XXIV, Heft 4, S. 398–416.

As far as it refers to the field of psycho-analysis, this paper points out that since psycho-analytic concepts are not only based upon private perceptions which cannot be directly experienced by anyone except the subject but assume the existence of mental states of which he himself is totally unaware, they are liable to be dismissed as fantastic or meaningless by other schools of thought, especially by the Behaviourists.

Nevertheless, those concepts can be established objectively and even be made to satisfy the standards of truth of Behaviourism. This is possible because most private perceptions are correlated with other perceptions and are accompanied by certain constant outward signs which can be observed by other people; so that the presence or absence of such associated perceptions and signs will indicate whether any given private perception is real or imaginary and thus whether any concepts based upon it are likely to be true. Their truth can, moreover, be further tested by seeing whether the consequences which would be expected to follow from them do in fact occur or not.