Overview
In psychoanalytic theory, Regression is a defense mechanism involving the reversion of the ego to an earlier stage of psychosexual development, as a reaction to an overwhelming external problem or internal conflict.
Sigmund Freud invoked the notion of regression in relation to his theory of dreams (1900) and sexual perversions (1905), but the concept itself was first elaborated in his paper "The Disposition to Obsessional Neurosis" (1913). In 1914, he added a paragraph to The Interpretation of Dreams that distinguished three kinds of regression, which he called topographical regression, temporal regression, and formal regression.
Freud, regression, and neurosis
Freud saw inhibited development, fixation, and regression as centrally formative elements in the creation of a neurosis. Arguing that "the libidinal function goes through a lengthy development", he assumed that "a development of this kind involves two dangers – first, of inhibition, and secondly, of regression". Inhibitions produced fixations, and the "stronger the fixations on its path of development, the more readily will the function evade external difficulties by regressing to the fixations".
Neurosis for Freud was thus the product of a flight from an unsatisfactory reality "along the path of involution, of regression, of a return to earlier phases of sexual life, phases from which at one time satisfaction was not withheld. This regression appears to be a twofold one: a temporal one, in so far as the libido, the erotic needs, hark back to stages of development that are earlier in time, and a formal one, in that the original and primitive methods of psychic expression are employed in manifesting those needs".
From Wikipedia (CC BY-SA 4.0).