This critique of Mahler's derivation of a developmental stage of normal symbiosis from her work with psychotic children reveals some clear parallels with Klein's description of the paranoid-schizoid position. The defence mechanisms of splitting, and of projective and introjective identification are already operative in the symbiotic stage and imply some distinction between self and other in the unconscious. Both theorists described the same confusion between self and other, but they attributed different explanations to the phenomenon. Whereas Mahler described the experience of feeling at one with the other, Klein elucidated the unconscious psychic mechanisms which operate to create this experience. The separation-individuation process has been redefined as the developing awareness of a sense of self, as distinct from earlier unconscious processes.