Nineteenth century According to historian of psychology Mark Altschule, "It is difficult—or perhaps impossible—to find a nineteenth-century psychologist or psychiatrist who did not recognize unconscious cerebration as not only real but of the highest importance." In 1890, when psychoanalysis was still unheard of,
William James, in his monumental treatise on psychology (
The Principles of Psychology), examined the way
Schopenhauer,
von Hartmann,
Janet,
Binet and others had used the term 'unconscious' and 'subconscious.'" German psychologists,
Gustav Fechner and
Wilhelm Wundt, had begun to use the term in their experimental psychology, in the context of manifold, jumbled
sense data that the mind organizes at an
unconscious level before revealing it as a cogent totality in conscious form."
Eduard von Hartmann published a book dedicated to the topic,
Philosophy of the Unconscious, in 1869.
Freud Sigmund Freud and his followers developed an account of the unconscious mind. He worked with the unconscious mind to develop an explanation for mental illness. For Freud, the unconscious is not merely that which is not conscious. He refers to that as the
descriptive unconscious and it is only the starting postulate for real investigation into the psyche. He further distinguishes the unconscious from the
pre-conscious: the pre-conscious is merely latent – thoughts, memories, etc. that are not present to consciousness but are capable of becoming so; the
unconscious consists of psychic material that is made completely inaccessible to consciousness by the act of
repression. The distinctions and inter-relationships between these three regions of the psyche—the conscious, the pre-conscious, and the unconscious—form what Freud calls the
topographical model of the psyche. He later sought to respond to the perceived ambiguity of the term "unconscious" by developing what he called the
structural model of the psyche, in which unconscious processes were described in terms of the
id and the
superego in their relation to the
ego. In the psychoanalytic view, unconscious mental processes can only be recognized through analysis of their effects in consciousness. Unconscious thoughts are not directly accessible to ordinary introspection, but they are capable of partially evading the censorship mechanism of repression in a disguised form, manifesting, for example, as dream elements or neurotic
symptoms. Such symptoms are supposed to be capable of being "interpreted" during psychoanalysis, with the help of methods such as
free association, dream analysis, and analysis of verbal slips and other unintentional manifestations in conscious life.
Jung Carl Gustav Jung agreed with Freud that the unconscious is a determinant of personality, but he proposed that the unconscious be divided into two layers: the
personal unconscious and the
collective unconscious. The personal unconscious is a reservoir of material that was once conscious but has been forgotten or suppressed, much like Freud's notion. The collective unconscious, however, is the deepest level of the psyche, containing the accumulation of inherited psychic structures and
archetypal experiences. Archetypes are not memories but energy centers or psychological functions that are apparent in the culture's use of symbols. The collective unconscious is therefore said to be inherited and to contain material of an entire species rather than of an individual. The collective unconscious is, according to Jung, "[the] whole spiritual heritage of mankind's evolution, born anew in the brain structure of every individual". In addition to the structure of the unconscious, Jung differed from Freud in that he did not believe that
sexuality was at the base of all unconscious thoughts. ==Dreams==