Originally introduced into psychoanalytic theory by Jung in 1911, the Latin term imago had already become standard in psychoanalytic terminology by the time Lacan began training as a psychoanalyst in the 1930s.
The term is clearly related to the term "image", but it is meant to emphasize the subjective determination of the image; in other words, it includes feelings as well as a visual representation.
Imagos are specifically images of other people.
However, they are not the product of purely personal experience but universal prototypes which may be actualized in anyone's psyche.
Imagos act as stereotypes influencing the way the subject relates to other people, who are perceived through the lens of these various imagos.
The term "imago" occupies a central role in Lacan's pre-1950 writings, where it is closely related to the term complex.
In 1938, Lacan links each of the three family complexes to a specific imago: the weaning complex is liked to the imago of the maternal breast, the intrusion complex to the imago of the counterpart, and the Oedipus complex to the imago of the father.
In 1946, Lacan argues that in formulating the concept of the imago, psychoanalysis has provided psychology with a proper object of study and thus set psychology on a truly scientific footing.
"It is possible.. to designate in the imago the proper object of psychology, exactly to the same extent that Galileo's notion of the inert material poitn formed the basis of phsyics."
Whereas for Jung and Klein imagos have equally positive and negative effects, in Lacan's work they are weighted firmly towards the negative, being funamentally deceptive and disruptive elements.
Lacan speaks of the imago of the fragmented body, and even unified imagos such as the specular image are mere illusions of wholeness which introduce an underlying aggressivity.
"The first effect of the imago which appears in the human being is an effect of subjective alienation.
After 1950 the term "imago" disappears almost entirely from Lacan's theoretical vocabulary.
However, the basis ideas developed around the term in Lacan's pre-1950 writings continue to play an important part in his thinking, being articulated around other terms, principally the term "image".