The psychoanalytic theory of schizophrenia usually explains the illness as a regression to the early oral, or adualistic phase of infancy, when the infant's ability to distinguish self and other is considered to be undeveloped. The schizophrenic symptoms of such regression include feelings of depersonalization and loss, phantasies of world dissolution, passivity, and archaic magical thinking.
Sullivan's psychoanalytic theory of schizophrenia was applied by Kantor and Winder in 1959. They elaborated the theory in process-reactive terms; the earlier the developmental stage to which the individual regresses, the more severe the schizophrenia, that is to say, the more it becomes process rather than reactive. In 1962, Goldman subsequently attempted to apply this general theory to specific aspects of regression in schizophrenia, for example, emotional and social behavior. He drew attention to the similarities of infants and schizophrenics in that both express diffuse emotion impulsively and unpredictably, with little stability of any emotional state.
In 1955, Arieti suggested a theory of progressive teleological regression in terms of neurological structure. He considered that when higher nervous centers, that is those developed later in the evolutionary sequence, are paralyzed by anxiety, lower nervous centers would predominate and thus reduce anxiety. The individual's readjustment to this level can not, however, be maintained because it is too deviant from normal functioning, so that further regression and deterioration is often inevitable. Psychoanalysts usually assume that no psychological crisis is ever fully resolved, and that traces of early part-resolved conflicts and partly satisfied needs will always persist into later life.