What was John Watson primarily known for in psychology?

John Watson is primarily known for his significant contributions to behaviorism, a major school of thought in psychology that emphasizes the study of observable behaviors over internal mental states. Watson believed that all behaviors are learned through interaction with the environment and that psychology should focus on this observable behavior rather than the unobservable mental processes. He argued that psychology should adopt the methods of natural sciences, promoting a scientific approach to understanding behavior.

Watson's work marked a departure from earlier psychological theories that focused more on the mind and consciousness. His famous experiment with "Little Albert" demonstrated how emotional responses could be conditioned, underscoring key behaviorist principles. This laid the groundwork for future research in behaviorism, influencing many approaches in psychology that followed.

The other options provided refer to different areas of psychology. The stages of cognitive development, for example, are attributed to Jean Piaget, while brain mapping relates to neuroscience and the physiological study of the brain. Contributions to perception involve understanding how we interpret sensory information, which is a different domain within psychology. Thus, Watson's designation as a key figure in behaviorism distinctly highlights his focus on behavior as the primary subject of psychological inquiry.