One of the most important studies into classical conditioning was done by Pavlov. In his experiment he aimed to prove how learning by association produces conditioned responses. To do this, he paired a neutral stimulus of a bell with a unconditioned stimulus of food to produce the unconditioned response of salivation in the dogs. Initially, salivation had only occurred when the dogs received food, howerever, by the end the once neutral stimulus of the bell could produce the conditioned response of salivation, meaning the bell had also become a conditioned stimulus. This shows how much of our behaviour is governed by learning through association, as behaviourist thinkers who believed all learning came from external influences and experience, aimed to prove.