Jean Piaget viewed intellectual growth in children as a process of adjustment to the world. This happens through thru assimilation, accommodation, and equilibration. For the 18th-month-old Mickey, his reaction (identifying and shouting to zebras as horses) is best demonstrated by Piaget’s concept of assimilation. Assimilation means the use of existing schema or mental model (zebra) to deal with the new object (horse) or situation.