From Classic Encyclopedia 1911
APPERCEPTION (Lat. ad and percipere, perceive), in psychology, a term used to describe the presentation of an object on which attention is fixed, in relation to the sum of consciousness previous to the presentation and the mind as a whole. The word was first used by Leibnitz, practically in the sense of the modern Attention, by which an object is apprehended as "not-self" and yet in relation to the self. In Kantian terminology apperception is (1) transcendental - the perception of an object as involving the consciousness of the pure self as subject, and (2) empirical, - the cognition of the self in its concrete existence. In (1) apperception is almost equivalent to self-consciousness; the existence of the ego may be more or less prominent, but it is always involved. According to J. F. Herbart apperception is that process by which an aggregate or "mass" of presentations becomes systematized (apperceptionssystem) by the accretion of new elements, either sense-given or product of the inner workings of the mind. He thus emphasizes in apperception the connexion with the self as resulting from the sum of antecedent experience. Hence in education the teacher should fully acquaint himself with the mental development of the pupil, in order that he may make full use of what the pupil already knows.
Apperception is thus a general term for all mental processes in which a presentation is brought into connexion with an already existent and systematized mental conception, and thereby is classified, explained or, in a word, understood; e.g. a new scientific phenomenon is explained in the light of phenomena already analysed and classified. The whole intelligent life of man is, consciously or unconsciously, a process of apperception, inasmuch as every act of attention involves the appercipient process.
See Karl Lange, Ueber Apperception (6th ed. revised, Leipzig, 1899; trans. E. E. Brown, Boston, 1893); G. F. Stout, Analytic Psychology (London, 1896), bk. ii. ch. viii., and in general text-books of psychology; also Psychology.