matching law
in operant conditioning, a law that describes the distribution of responses when numerous task options are available. It states that the proportion of responses allocated to an alternative will match the proportion of reinforcement obtained from that alternative. For example, if a pigeon receives two thirds of its food allocation from Alternative A and one third from Alternative B, it will make two thirds of its responses (and give two thirds of its time) to Alternative A. If the pigeon makes fewer than two thirds of its responses to Alternative A—that is, has less sensitivity to reinforcement than the law predicts—then undermatching has occurred. If, however, the pigeon makes more than two thirds—that is, has greater sensitivity to reinforcement than the law predicts—then overmatching has occurred. See also generalized matching law.