SUBLIMINAL SELF. The phrase owes its wide currency to the writings of F. W. H. Myers, especially to his posthumous work Human Personality and its survival of Bodily Death. In the stricter usage the phrase stands for an hypothesis which seemed to its author to bring almost all the strange facts he ob served under one scheme of explanation. But the phrase "Sub liminal Self" is now often used by those who do not fully accept Myers's hypothesis, as a convenient heading to which to refer all the facts of many different kinds that seem to imply subconscious or unconscious mental operations. It is the stricter sense that here concerns us.
In the speculations of Schopenhauer and of Eduard von Hart mann, the "Unconscious" played a great part as a metaphysical principle explanatory of the phenomena of the life and mind of both men and animals. But with these exceptions, the philoso phers and psychologists of the 19th century showed themselves in the main reluctant to admit the propriety of any conception of unconscious or subconscious mental states or operations. The predominant tendency was to regard as the issue of "automatic" nervous action or of "unconscious cerebration" whatever bodily movements seemed to take place independently of the conscious ness and volition of the subject, even if those movements seemed to be of an intelligent and purposeful character. This attitude towards the subconscious is still maintained by some of the more strictly orthodox scientists : but it is now very widely accepted that we must recognize in some sense the reality of subconscious ness or of subliminal pyschical process. The conception of a limen (threshold) of consciousness, separating subconscious or subliminal psychical process from supraliminal or conscious psychical process, figured prominently in the works of G. T. Fechner, the father of psycho-physics, and by him was made widely familiar. In the last half century, there has been accumu lated a mass of observations which establish the reality of proc esses which express themselves in purposeful actions and which bear all the marks from which we are accustomed to infer con scious cognition and volition, but of which nevertheless the sub ject or normal personality has no personal knowledge.
Among the commonest and most striking of such manifesta tions is the "automatic writing" which a considerable proportion of normal persons are capable of producing. A person who has this power may sit absorbed in reading or in conversation, while his hand produces written words or sentences, of which he knows nothing until he afterwards reads them. In some cases the matter so written states facts previously known to the subject but which he is unable to recollect by any voluntary effort. And in rare cases the matter written seems to imply knowledge or capacities which the subject was not believed to possess either by himself or by his friends. Other actions, including connected speech, may be pro duced in a similar fashion, and in the last case the subject hears and understands the words uttered from his own mouth in the same way only as those from the mouth of another person. "Table tilting," "planchette-writing," and the various similar modes of spelling out by the aid of a code intelligible replies to ques tions, which have long been current in spiritistic circles and which, by those who practise them, are often regarded as the operations of disembodied intelligences, seem to belong to the same class of process. In extreme cases the manifestations of such subconscious or (better) co-conscious operations are so fre quent, exhibit so much continuity and express so clearly a train of thought, purpose and memory, that they compel us to infer an organized personality of which they are the expression; such are the cases of double or multiple consciousness or personality. Very similar manifestations of a "co-consciousness" may be produced in a considerable proportion of apparently normal persons by means of post-hypnotic suggestion; as when suggestions are made during hypnosis, which afterwards the subject carries out without being aware of the actions, or of the signals in response to which he acts, and without any awareness or remembrance of the nature of the suggestions made to him. The more sober-minded of the investigators of these phenomena have sought to display all such cases as instances of division of the normal personality, and as explicable by the principle of cerebral dissociation (see HYPNO