The evolution of behaviourism marks a significant shift in the history of psychological thought from the introspective study of consciousness to the objective study of observable behaviour. Behaviourism emerged in the early twentieth century as a reaction against structuralism and functionalism, both of which relied heavily on introspection. Introspection was criticized for being subjective, unreliable, and incapable of producing verifiable scientific data. In this intellectual climate, behaviourism developed as a movement that sought to establish psychology as a natural science grounded in observable and measurable phenomena. The roots of behaviourism can be traced to earlier philosophical traditions such as British empiricism. Thinkers like John Locke proposed that the mind at birth is a tabula rasa, a blank slate, and that knowledge arises from experience. This emphasis on experience laid the groundwork for later associationist theories, which suggested that ideas become linked through repeated experiences. These ideas influenced early learning theorists and prepared the way for a scientific analysis of behaviour. A major influence on behaviourism came from Russian physiologist Ivan Pavlov. Although Pavlov was not a psychologist, his experiments on classical conditioning provided empirical evidence that behaviour could be studied objectively. Pavlov demonstrated that dogs could learn to associate a neutral stimulus, such as a bell, with food, eventually producing salivation in response to the bell alone. This process of conditioning showed that behaviour could be explained in terms of stimulus-response connections formed through experience. Pavlov’s work offered a model of learning that was precise, measurable, and replicable, qualities that appealed strongly to early behaviourists. The formal beginning of behaviourism is generally associated with John B. Watson. In 1913, Watson published his seminal paper, “Psychology as the Behaviorist Views It,” often referred to as the behaviourist manifesto. Watson rejected the study of consciousness and mental states, arguing that psychology should focus exclusively on observable behaviour. He defined psychology as the science of behaviour and emphasized prediction and control as its primary goals. Watson believed that behaviour could be explained entirely in terms of environmental stimuli and responses, without reference to internal mental processes. His famous experiment with “Little Albert” demonstrated how emotional responses could be conditioned, reinforcing his claim that complex behaviours could be built from simple stimulus-response associations. Following Watson, behaviourism was further developed and refined by several psychologists. Edward Thorndike contributed the Law of Effect, which stated that responses followed by satisfying consequences are more likely to recur, while those followed by discomfort are less likely to be repeated. Thorndike’s work on