The field of psychology began to pay attention to childhood development in the 20th century, and psychoanalytic theories of childhood development suggest that children go through stages to develop while cognitive theories say children are active learners. Behavioral theories suggest the environment can influence a child's development. Social child development theories focus on society's role in the development of children.
Sigmund Freud and Erik Erikson both developed psychoanalytic theories of childhood development. Both psychologists felt children go through stages that can impact their lives as adults. Freud believed the stages were psychosexual stages called genital, latency, phallic, anal and oral stages, during which a child would need to fulfill a desire to move past the stage and continue to develop, with serious consequences in adulthood if the stage was not completed. Erikson believed different stages happened throughout a person's lifetime, not just in childhood, and that conflicts had to be overcome to finish a stage. If the child failed to overcome a conflict, such as developing his own identity, then the child would suffer later in life by not knowing who he was.
The cognitive theories of childhood development were developed by Jean Piaget. This theory says children think very differently than adults do and go through various cognitive development stages as they grow older. Piaget believed children are active learners who need adults to provide the proper environment in which to learn. This theory has shaped many school and preschool curriculums.
Behavioral theories of childhood development do not take into account how a child feels or thinks. These theories, developed by John B. Watson, B.F. Skinner and Ivan Pavlov, focus on behavior that can be observed only. This theory says a child's development depends on the reinforcements, punishments, rewards and stimuli that he experiences and that these experiences are what shape children into the adults they become.
Lev Vygotsky, Albert Bandura and John Bowlby developed social theories of childhood development. Vygotsky developed the sociocultural theory and felt children learned by hands-on activities and that adults such as parents and teachers — as well as all of society — was responsible for the way a child developed. Bandura created the social learning theory and believed children learn new things by watching those around them and by paying attention to internal feelings such as pride. Bowlby believed the relationships children develop with primary caregivers soon after birth influence both the child's development and his relationships throughout his life. Bowlby's theory is popular with those who practice attachment parenting.