cognitive psychology, school of psychology that examines internal mental processes such as problem solving, memory, and language. It had its foundations in the Gestalt psychology of Max Wertheimer, Wolfgang Köhler, and Kurt Koffka, and in the work of Jean Piaget, who studied intellectual development in children. Cognitive psychologists are interested in how people understand, diagnose, and solve problems, concerning themselves with the mental processes which mediate between stimulus and response. Cognitive theory contends that solutions to problems take the form of algorithms—rules that are not necessarily understood but promise a solution, or heuristics—rules that are understood but that do not always guarantee solutions. In other instances, solutions may be found through insight, a sudden awareness of relationships. Cognitive psychologists have tried to reach a greater understanding of human memory (see memory) and language. In recent years, cognitive psychology has become associated with information processing, which examines artificial intelligence in computers to find out whether they are capable of problem solving in ways similar to humans. Information processing theory studies the parallels between the human brain and the computer, in the ways that both can receive, process, store, and retrieve information.

Mental conflict that occurs when beliefs or assumptions are contradicted by new information. The concept was introduced by the psychologist Leon Festinger (1919–89) in the late 1950s. He and later researchers showed that, when confronted with challenging new information, most people seek to preserve their current understanding of the world by rejecting, explaining away, or avoiding the new information or by convincing themselves that no conflict really exists. Cognitive dissonance is nonetheless considered an explanation for attitude change.

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