Cognitive Development

There are many different types of changes that occur over the course of a child's development. In general, cognitive development refers to the changes over time in children's thinking, reasoning, use of language, problem solving, and learning. The field is vast and researchers across the world study many different aspects of children's thinking at different points in development. For example, some researchers are interested in changes during infancy, such as when a baby recognizes her caregivers, remembers simple events, and understands the language spoken around her. Some researchers examine toddlers to learn how young children progress in their use of language and their understanding of the perspectives of the people around them. The early school years are studied to learn how children become more sophisticated in their ability to solve problems and use their memories. Yet others are interested in the possible changes in academic performance of school-age children and adolescents when they transition from grade school to middle school or from middle school to high school.

Although developmental psychologists begin their work by charting the changes they see in the developing human, their ultimate goal is to explain how those changes came about. This is challenging because humans are dynamic, complex beings who are shaped by different people and events. It is often difficult to draw conclusions about exactly which influences and experiences are most important for particular aspects of cognitive development. Thus, psychologists examine a variety of influences including changes in the brain, the influence of parents, the effect of a child's interaction with siblings and peers, and the role of culture. Typically, in order to accurately characterize aspects of development, psychologists must consider interactions between physiological changes in the brain and the child's social environment. For example, people often use child-directed speech when talking with young children. This type of language accentuates word boundaries and is spoken more slowly compared to adult-directed speech. This aspect of the child's environment may interact with changes in the baby's brain to help the baby comprehend the language spoken around her.

Three theories have had a substantial influence on research in cognitive development. It is important to examine these theories, and a subset of the key experimental demonstrations that support them, to understand how each perspective emphasizes different influences as critical to a child's development. Interestingly, historical trends in the field can often be explained by understanding which theory was most influential during various periods over the last half of the twentieth century.

The first major theory of cognitive development emerged during the 1950s when the work of Swiss psychologist Jean Piaget was discovered and translated. A second major theory of cognitive development, known as the sociocultural theory, can be attributed to translations of work done by Russian psychologist Lev Vygotsky, who was a contemporary of Piaget. A final important class of theories, information-processing theories, has focused on the child's ability to process information and emerges from an interaction between environmental influences and physiological changes in the child's brain. These three theoretical perspectives have been influential for more than half a century and continue to inform developmental research that is conducted in the early twenty-first century.