Quasi-reinforcement and behavioral contrast

The quasi-reinforcement effect occurs when a stimulus, produced in the same manner as a current reinforcer, produces a reinforcement effect. The effect is of interest since the quasi-reinforcer is explicitly nonpaired with the current reinforcer. The traditional account of acquired or "conditioned" reinforcement is based on close spatio-temporal pairing of a stimulus with a current reinforcer. Hence, the effect suggests an alternative account of the genesis of acquired reinforcement.

The procedure to produce the quasi-reinforcement effect is one member of a class termed second-order reinforcement schedules. The common view of second-order schedule reinforcement effects is that the contingent event functions not as a genuine reinforcer but produces discriminative effects on performance that only resemble reinforcement.

The specific purpose of the present experiments was to provide a test that would differentiate between these two views: the quasi-reinforcer as a reinforcer versus only a discriminative signal. It was proposed that, if the quasi-reinforcer was a reinforcer, then it should show other functional properties of reinforcers beyond its immediate control of the temporal pattern of responding. These experiments examined whether the manipulation of the presence of a quasi-reinforcer in a multiple schedule would produce positive behavioral contrast, an effect often found, for example, with changes in the rate of food-reinforcement.

The results showed that the quasi-reinforcer did produce positive behavioral contrast effects. Contrast effects were obtained with two types of response requirements. This showed that the results were not dependent upon a particular response requirement. An experiment showed that it was the second-order schedule relationship between the quasi-reinforcer and food that was critical to the effects. Neither reinforcement nor positive behavioral contrast effects were obtained with a conjoint reinforcement schedule, which provided both the same quasi-reinforcer and food at the same rate but lacking the second-order relationship. Another experiment manipulated food rate. The results showed the same pattern of contrast effects as occurred with the quasi-reinforcer alone.

The results were consistent with the view that the quasi-reinforcer functioned as a genuine reinforcer. The general significance of the pigeon's sensitivity to the differences in these complex schedule relationships was emphasized in the discussion.