The term gender identity, meaning a person's relative sense of his or her own masculine or feminine identity, was first used in 1965 by John Money (Money, 1965). The term was introduced into the psychoanalytic literature by Robert Stoller in 1968 (Stoller, 1968). Money used the term to distinguish the subjective experience of gender from the concept of "gender role" which he used to describe the socially determined attributes of gender. Stoller (1968) developed the idea further to distinguish between the psychological and biological dimensions of sex. He used gender to distinguish ideas and experiences of masculinity and femininity—both socially determined psychological constructs—from sex, the biologically determined traits of maleness and femaleness. This usage has become the standard in psychoanalytically derived discussions of gender and sexuality to refer to the psychological aspects of sexuality, what Freud (1925) called "psychical consequences of the anatomical distinction between the sexes." Stoller (1968) further distinguishes the general sense of masculinity and femininity—gender identity—from the earlier awareness of sexual difference, what he calls core gender identity, a relatively fixed sense of maleness or femaleness usually consolidated by the second year of life, prior to the oedipal phase. Stoller identifies three components in the formation of core gender identity: 1) Biological and hormonal influences; 2) Sex assignment at birth; 3) Environmental and psychological influences with effects similar to imprinting. In contrast to Freud's belief that the primary identification is masculine, Stoller believes that both the boy and the girl begin with a female core gender identity obtained from the maternal symbiosis. Core gender identity is derived non-conflictually through identification and, in essence, learning. Failure to interrupt the maternal symbiosis pre-oedipally with boys may result in permanent core gender identity disorders like transsexualism. Otherwise, normal development facilitates the boy's shift to a male core gender identity and the subsequent oedipal conflicts associated with obtaining a masculine gender identity. The concept of gender identity is important historically because it separates masculine and feminine psychology from the innate biological determinism suggested by Freud. Increasing attention to the diversity and multiplicity of the origins and workings of gender have made even the terms gender identity and core gender identity less than adequate to describe the nuances of such a central organizing factor of personality and behavior. It is important to differentiate the term, gender identity, which describes the individual's sense of gender, from Stoller's speculative theory about the origins of core gender identity.