Tiedemann (1787) and Darwin (1877) provided the first systematic notes on infancy / among the issues explored by both was the question of when infants could first recognize themselves in a "looking glass" and begin fashioning a self-concept / both were convinced that by about two years of age infants could recognize themselves and had developed at least a primitive notion of self
the principal point I will try to make is that experiments can also be directed toward the initial origins of the notion of self—its foundation and earliest manifestation in the preverbal child / recent studies of imitation and related phenomena in infancy provide new insights that complement the work that has already been done with mirror recognition / moreover, because these studies involve infants younger than those used in the mirror test, they allow a glimpse of an even more embryonic notion of self than is reflected in the mirror studies
argue that these recent studies have uncovered aspects of the primordial notion of self from which subsequent development proceeds / by understanding the initial condition of the self during early infancy, we can better understand the subsequent critical developments that occur at eighteen to twenty-four months, when children are acquiring language and finally become able to recognize themselves in a mirror (PsycINFO Database Record (c) 2012 APA, all rights reserved)