"Mirror stage" refers to the point in time when infants and toddlers start recognizing their reflections in the mirror. Research has shown that, although babies are fascinated with images of themselves and others in mirrors from a very early stage, they do not begin to recognize that the images in the mirror are reflections of their own bodies until the age of about 15 to 18 months. In psychology, there has been a debate about the mirror stage's importance in identity formation.
In 1936, psychologist Jacques Lacan proposed that the mirror stage was part of an infant's development from 6 to 18 months. By the early 1950s, Lacan's concept of the mirror stage had changed slightly; he no longer considered the mirror stage as a moment in the life of the infant, but as representing a permanent structure of identity. Lacan felt that understanding and processing one's reflection was a key part in the development of identity.
In 1953, Lacan wrote, "The mirror stage is a phenomenon to which I assign [two values]. In the first place, it has historical value as it marks a decisive turning point in the mental development of the child."

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