during one period of research, he described himself studying his own three children, and carefully observing and interpreting their cognitive development. In one of his last books, Equilibration of Cognitive Structures: The Central Problem of Intellectual Development, he intends to explain knowledge development as a process of equilibration using two main concepts in his theory, assimilation and accommodation, as belonging not only to biological interactions but also to cognitive ones.

He stated that children are born with limited capabilities