According to Piaget (1936/1952), the development of children's manipulations of objects during the second year of life is simply a continuation of the development of their object manipulations as infants. He did not see a major qualitative difference between children's object-centered actions during the first and second years, which made it possible for him to designate the first 2 years of life as belonging to the same sensorimotor period of development. In contrast, following Vygotsky (1984/1998), Russian neo-Vygotskians emphasize a major difference between object-centered actions during the first and second years (Elkonin, 1978, 1989; Lekhtman-Abramovich & Fradkina, 1949; Zaporozhets & Lisina, 1974).

Until the end of the first year of life, infants manipulate objects in accordance with their physical characteristics: shaking a rattle, pushing a ball, and so on. Of course, Russian neo-Vygotskians would not deny that such independent manipulations of objects in accordance with their physical characteristics can often be observed during the second and even the third years of life. Neither would they undermine the importance of such manipulation for the child's learning different physical properties of objects and the environment in general. The neo-Vygotskians, however, give major emphasis to another type of children's object-centered actions, which become typical of children during the second and third years of life. These are actions with objects in accordance with their social meanings, which include, but are not limited to, children's play actions with different toys.