law of effect
broadly, the principle that consequences of behavior act to modify the future probability of occurrence of that behavior. As originally postulated by Edward L. Thorndike, the law of effect stated that if a response R produces a satisfying state of affairs (or a positive reinforcer), then an association is formed between R and the stimuli S present at the time R was made. As a result of this S–R association, R occurs whenever the organism encounters S. This part of the law of effect was the foundation of S–R theories of learning. Originally, Thorndike also proposed that the presentation of an aversive or annoying consequence serves to weaken S–R associations, with the consequence that responding becomes suppressed. He later revised the law to include only the response-strengthening effect of reinforcement; the original version of the law was called the strong law of effect, and the revised version was known as the weak law of
effect.