Piaget has been criticized for relying almost exclusively on the intellectual content of knowledge. Piaget paid little attention to the impact of culture, emotion, observational learning, and verbal instruction on cognitive development. Indeed, later research has shown that children’s (and adults’) knowledge of the world is greatly impacted by all of the above factors. Nonetheless, this does not invalidate Piaget’s contributions; it simply shows that his work is limited in scope. He cannot explain all of children’s mental life, but he did tell us a tremendous amount about early cognitive development.