The ontogenesis of smiling and laughter: a perspective on the organization of development in infancy.

From a consideration of developmental data an integrative perspective on infant development is evolved emphasizing the function of the smile. From the earliest spontaneous smiles of the newborn period to mature smiling and laughter, a central role was revealed for an eAcitation (tension) relaxation process in producing smiles, This notion is complementary to social and cognitive .theories of smiling but is lore . basic in pointing to the function of the smile for the infant and in stressing continuity of smiles following mastery and smiles following excitation, In unraveling the changing meaning of the smile a number of developmental principles were .revealed, including the following: (a) developmntal sequences may be repeated!, though in,a transformed and elaborated manner, (b) ttie'infant becomes increasingly active in produc-