The tendency to choose a larger, more delayed reinforcer over a smaller, less delayed one has frequently been termed “selfcontrol.” Three very different research traditions – two models emphasizing the control of local contingencies of reinforcement (Mischel's social learning theory and Herrnstein's matching law) and molar maximization models (specifically optimal foraging theory) – have all investigated behavior within the self-control paradigm. A framework is proposed to integrate research from all three research areas. This framework consists of three parts: a procedural analysis, a causal analysis, and a theoretical analysis. The procedural analysis provides a common procedural terminology for all three areas. The causal analysis establishes that, in all three research traditions, self-control varies directly with the current physical values of the reinforcers; that is, choices increase with reinforcer amount and decrease with reinforcer delay. But self-control also varies according to past events to which a subject has been exposed, and according to current factors other than the reinforcers. Each of the three models has therefore incorporated these indirect effects on self-control by postulating unobservable mechanisms. In all three cases, these mechanisms represent a subject's behavior as a function of a perceived environment. The theoretical analysis demonstrates that evolutionary theory can encompass the research from all three areas by considering differences in the adaptiveness of self-control in different situations. This integration provides a better and more predictive description of self-control.

Kahneman and Tversky's cognitive model of human choice is compared with Herrnstein's behavioral model of animal choice. The two models have many corresponding concepts. A means is proposed for translating between the models so as to provide behavioral descriptions of cognitive experiments and cognitive descriptions of behavioral experiments. One important bridge between the two models is the correspondence between the concept of probability in the cognitive model and the concept of delay in the behavioral model. The behavior of human subjects who fail to choose a gamble of the highest expected value may correspond to the behavior of animal subjects who fait to choose the highest overall rate of reward. In the cognitive model such inconsistent behavior is ascribed to nonlinear subjective weighting of amounts or probabilities. In the behavioral model such behavior is ascribed to the sharp discounting of delayed rewards-a problem of self-control. We argue that these are just two competing descriptions of a single fundamental process.

Pigeons chose between an immediate 2-second reinforcer (access to grain) and a 6-second reinforcer delayed 6 seconds. The four pigeons in the control group were exposed to this condition initially. The four experimental subjects first received a condition where both reinforcers were delayed 6 seconds. The small reinforcer delay was then gradually reduced to zero over more than 11,000 trials. Control subjects almost never chose the large delayed reinforcer. Experimental subjects chose the large delayed reinforcer significantly more often. Two experimental subjects showed preference for the large reinforcer even when the consequences for pecking the two keys were switched. The results indicate that fading procedures can lead to increased "self-control" in pigeons in a choice between a large delayed reinforcer and a small immediate reinforcer.

In five experiments, choice responding of female human adults was examined, as a function of variations in reinforcer amount and reinforcer delay. Experiment 1 used a discrete-trials procedure, and Experiments 2, 3, 4, and 5 used a concurrent variable-interval variable-interval schedule. Reinforcer amount and reinforcer delay were varied both separately and together. In contrast to results previously reported with pigeons, the subjects in the present experiments usually chose the larger reinforcers even when those reinforcers were delayed. Together, the results from all the experiments suggest that the subjects followed a maximization strategy in choosing reinforcers. Such behavior makes it easy to observe self-control and difficult to observe impulsiveness in traditional laboratory experiments that use adult human subjects.