behaviour

Behaviour, also spelled behavior, is the observable actions and reactions of a living organism in response to internal or external stimuli. It encompasses motor activities such as movement and gestures, vocalizations, and physiological responses that can be measured indirectly through indicators like heart rate or pupil dilation. Behaviour contrasts with internal mental states, but in practice they interact continually.

Scholarly approaches to behaviour vary. In psychology, behaviourism emphasizes the study of observable actions and the role of environmental contingencies, while other theories focus on cognition, emotion, and motivation. In biology and ethology, behaviour is viewed as the product of evolutionary processes, neural mechanisms, and hormonal influences, and is often studied in natural contexts such as animal communication, foraging, mating, and social structure.

Behaviour can be innate or learned. Innate behaviours are present at birth and do not require experience, such as reflexes; learned behaviours arise through conditioning, imitation, problem solving, or social learning. Behaviours may be adaptive, enhancing survival or reproductive success, or maladaptive, reducing fitness in certain environments. Social behaviour covers interactions within and between species, including cooperation, aggression, communication, and cultural practices.

Influences on behaviour include genetics, development, environment, reinforcement, and social norms. Researchers study behaviour through observation, experiments, and naturalistic studies, while ethical principles guide research involving humans and animals. Applications span education, clinical treatment, animal welfare, conservation, and user-centered design, where understanding behaviour informs interventions, policy, and systems that support desired outcomes.