Behavior in psychology encompasses all observable human and animal actions, as well as covert cognitive, emotional, and physiological processes that underlie them. Historically, the formal study of behavior transitioned from philosophical introspection to empirical science with the establishment of Wilhelm Wundt's psychological laboratory in Leipzig, Germany, in 1879.
- Structuralism (Wundt & Titchener): Focused on breaking down mental processes into the most basic components using the method of introspection.
- Functionalism (William James): Influenced by Charles Darwin, it emphasized the adaptive, functional utility of consciousness and behavior in helping organisms adapt to their environments.
- Behaviorism (Watson, Skinner, Pavlov): Radical behaviorism rejected unobservable mental states, asserting that psychology must focus exclusively on measurable stimulus-response (S-R) relationships. John B. Watson (1913) famously declared psychology a purely objective experimental branch of natural science.
- Cognitive Revolution: Championed by figures like Ulric Neisser and Jean Piaget, this perspective reintroduced internal mental states—such as memory, perception, and problem-solving—as legitimate subjects of scientific inquiry, utilizing the computer metaphor of information processing.