These elements, which come from Ferdinand de Saussure's linguistic theory, were introduced and problematized in the field of psychoanalysis by Jacques Lacan during his "return to Freud" phase in the early 1950s.
Lacan relied on the following main points of Saussure's structural model.
The directed and temporal sequence of an articulation presupposes the division of language into two axes: the syntagmatic axis, which refers to a system of speech as a system of signs capable of being combined and concatenated, and the paradigmatic axis, which refers to a system of language as a system of signs selected and substituted for particular meanings.
A sign taken in isolation does not define a meaning: a signifier can refer to several signifieds. Each sign thus gains its value by being placed in the context of other signs. The "break" between a flow of sounds and a flow of thought associates the signifier with a signified.
Freud's definition of psychoanalysis as a treatment through speech led Lacan to propose that the "unconscious is structured like a language." This theory, advanced and developed on the basis of Freud's work, led Lacan to assign to the signifier and to the structure of language a fundamental role in the unconscious processes of the speaking subject.
At the level of the expressions of the unconscious, the elaboration of symptoms appears to be analogous to the mechanisms of metaphor, while witticisms and slips of the tongue appear to be analogous to metaphorical condensation and/or metonymic displacement.
The dynamic of desire in the speaking subject is expressed in an indefinite sequence of signifiers operating metonymically. However, this notion only holds because Lacan transformed Saussure's definition of the linguistic sign and, more specifically, that of the signifier in the structure of language. He referred to this as his "linguisteria" (linguistérie).
The bar that separates S from s shows the relationship between the subject and the language. The subject is thus subordinated to signifiers, without always having access to the meaning that they delimit. This is seen clearly in psychotic discourse, which unleashes the signifier.
Lacan replaced Saussure's "break" (coupure), Saussure's correspondence between the flow of signifiers and the flow of signifieds, with the point de capiton (literally, "quilting stitch"), the operation that stops the indefinite slippage of meaning by making a deferred limitation.
The logic of the signifier thus defined by Lacan calls for a change in how the unconscious processes are analyzed. Lacan focused on how the unconscious expresses itself in the patient's language, as revealed through meter, punctuation, and interpretative breaks. Within this logic, certain signifiers, such as "phallus", "Name-of-the-Father", and "lack in the Other", are invested with a fundamental metapsychological value.
In Lacan's pre-1950 writings, the term 'signification' is used in a general way to connote both meaningfulness and importance (e.g. Ec, 81).
In 1946, for example, Lacan criticises organicist psychiatry for ignoring 'the significations of madness' (Ec, 167; see Ec, 153- 4).