ABSTRACT
Five decades of laboratory research have confirmed millennia of commonsense observation: Action is indeed affected by its consequences. Just as research on concepts and equivalence relations broadened the class of effective antecedent stimuli, so the demonstration of response-reinforcer relativity broadened the class of effective consequences to include all activities of higher probability than the response being reinforced. All of the research and theory reviewed involved steady-state behavior—that is, behavior maintained under constant conditions of reinforcement until it stabilized at a rate characteristic of those conditions. If a therapist seeks to establish some desired behavior so that it will persist through the vicissitudes of daily life, a high frequency of reinforcement is recommended. At the end of The Origin of Species, C. Darwin invites us to contemplate a tangled bank, with its plants and its birds, its insects and its worms; to marvel at the complexity, diversity, and interdependence of its inhabitants
