This topic was most voted for in this week’s poll at the moment of publication of this article was the theory of the Four Stages of Cognitive Development! This theory was devised by Jean Piaget, and mainly spoke about children. Though he was not the first person to be involved in child psychology, there is no denying that Jean Piaget’s contributions to this subfield of psychology have had immense influences. He did many things besides psychology, such as history and philosophy, and he got involved in children’s education, as he thought that was very important.