Cognition is the set of mental processes that include thinking, knowing, remembering, judging, and problem-solving. It encompasses the higher-level functions of the brain and the ways in which people acquire, process, and use information.

Cognitive psychology emerged as a distinct field in the mid-twentieth century, reacting against behaviorism’s exclusion of mental life. Researchers developed experimental methods to infer internal processes from observable performance—reaction times, error patterns, and later brain imaging. Topics range from attention and perception through memory, language, decision making, and expertise. Cognitive science broadens the enterprise further by incorporating insights from linguistics, computer science, philosophy, and neuroscience.

Cognition is not a single faculty. It is a collection of interacting systems, some specialized and some general, some conscious and some automatic. Individual differences in cognitive ability predict educational and occupational outcomes, yet cognition is also highly trainable within limits. Age, fatigue, emotion, and culture all modulate how cognitive processes operate.

Whenever a person interprets a sentence, recalls a name, or chooses among options, cognition is at work.