BEHAVIORAL-CONTRAST WITH CHANGES IN DURATION AND RATE OF REINFORCEMENT

Behavioral contrast can be defined as an inverse relation between rate of responding in one component of a multiple schedule and conditions of reinforcement in the other components. The present study was an att empt to produce contrast with changes in duration of reinforcement. Pi geons pecked a key for mixed grain delivered by a multiple variable-in terval variable-interval schedule. In Experiment 1, the reinforcer dur ation in the second component was decreased or increased, for differen t subjects, by a factor of two, four, and six from that delivered duri ng baseline. These changes usually produced contrast. In Experiment 2, rate, duration, or rate and duration of reinforcement varied in the s econd component. Contrast was usually observed when only one variable was manipulated. When both variables were manipulated in the same cond ition, but in opposite directions, responding in the constant componen t usually changed inversely with the change in rate of reinforcement, not the change in reinforcer duration. The results demonstrate that ch anges in duration of reinforcement can produce contrast. They also inc rease the empirical base for which a successful theoretical account of contrast must encompass and the generality of contrast, which increas es its potential practical implications. (C) 1997 Elsevier Science B.V .