Developmental psychology is the branch of
psychology devoted to the study of age-related changes in behavior in both humans and other species. The branch has theoretical implications for all fields of psychology and many practical applications, for example, by providing more effective techniques for teaching children who are developmentally delayed. More recently,
lifespan psychology[?] has extended the focus of study to adult development, considering systematic change from conception to death as its subject. The areas covered include cognitive, physical, and psychosocial development. Some of the most influential contributors to the field include
William James,
Jean Piaget,
Lev Vygotsky,
Sigmund Freud,
Erik H. Erikson, and
Heinz Werner[?].