In 1911, Edward L. Thorndike, a graduate student at Columbia University, published a book titled Animal Intelligence. Saying that the work done in comparative psychology thus far “[had] all been about animal intelligence, never about animal stupidity” (Thorndike, 1911, p. 22), and that the theories about animal intelligence were generally based on anecdotes, he devised a simple, behavioristic explanation of learning. After conducting a series of meticulous experiments on dogs, cats and chicks, he found that the results of his experiments “[seemed] to disprove the existence of any rational faculty in the subjects experimented on” (Thorndike, p. 75). Thus, he ascribed learning to imitation and the forming of instinctual associations.
Thorndike put cats in puzzle boxes and observed their behaviour, sometimes placing food outside the boxes to motivate the cats to escape. The cats could escape from the boxes by a variety of methods, such as pulling a string or pushing a lever. Thorndike found that the cats learned by trial and error which action would help them escape soonest. When a cat was put in a box, it would go through a range of instinctive movements before chancing upon the one that would free it. The next time it was put in the box, it would repeat its previous behaviour, but perhaps escape a little sooner. The time taken to escape decreased gradually with each trial. Thorndike theorised that the cat escaped increasingly quickly because it learnt to associate the correct movement with freedom from its box, and not because it had come to understand how to escape. He pointed out that if the cat’s shorter escape times were due to reason, its speed of escaping would have increased abruptly at the point of gaining that particular insight. Instead, the cat’s performance increased slowly and inconsistently. Based on these experiments, Thorndike (1911) formulated the Law of Effect, which stated:
Of several responses made to the same situation, those which are accompanied or closely followed by satisfaction to the animal will, other things being equal, be more firmly connected with the situation, so that, when it recurs, they will be more likely to recur; those which are accompanied or closely followed by discomfort to the animal will, other things being equal, have their connections with that situation weakened, so that, when it recurs, they will be less likely to occur. The greater the satisfaction or discomfort, the greater the strengthening or weakening of the bond. (p. 244)
This type of learning is classified as operant conditioning, where the subject operates on the environment to produce an outcome. Kalat (2005) defines operant conditioning as “the process of changing behaviour by following a behaviour with reinforcement” (p. 207). It differs from classical conditioning in its procedure; in classical conditioning, the subject’s behaviour has no impact on the outcome of the situation.