Developmental psychology is the scientific study of how and why human beings change over the course of their life. This includes cognitive development and how children think, explore and figure things out. It is the development of knowledge, skills, problem solving and dispositions, which help children to think about and understand the world.
Cognitive Psychologists
Lev Vygotsky: developed research on cognitive abilities of children, and how children are influenced through social aspects of such as culture. (He studied children's memory and problem solving.)
Jean Piaget: developed research on cognitive development as children age into adulthood. He concluded that there were four stages in a child's development, sensorimotor, preoperational, concrete operational, and formal operational.
Albert Bandura: developed research on aggressive behavior in children, including modeling and observation.
Diana Baumrind: developed research on parenting styles, and the effect on their child's development.
Konrad Lorenz: developed research on attachment of children, specifically imprinting.
Harry Harlow: developed research on love in children. Famous for the experiment studying infant monkeys .
Mary Ainsworth: developed research on attachment on children to their parents.
Sigmund Freud: developed research on sexual stages of childhood.
Lawrence Kohlberg: developed research hand theories on moral development.
Erik Erikson: developed theories on the stages of psychosocial development