The concept of childhood is relatively new; in most medieval societies, childhood did not exist. At approximately 7 years of age, children were considered little adults with similar expectations for a job, marriage, and legal consequences. Charles Darwin advanced ideas about childhood development in his work on the origins of ethology (the scientific study of the evolutionary basis of behavior) and in "A Biographical Sketch of an Infant," first published in 1877. It wasn't until the 20th century that developmental theories emerged. When conceptualizing cognitive development, we cannot ignore the work of Jean Piaget. Piaget suggested that when young infants experience an event, they process new information by balancing assimilation and accommodation. Assimilation is the process of taking in new information and fitting it into previously understood mental schemas. Accommodation is the adaptation and revision of a previously understood mental schema in response to novel information. Piaget divided child development into 4 stages.
Copyright © 2026, StatPearls Publishing LLC.