The Interactive Schedule: A Common Conceptualization for Ratio and Interval Schedules

Abstract

A new mathematical method for specifying response-time-reinforcement contingencies is presented and called the interactive schedule. It allows the experimenter to specify schedule of reinforcement characteristics along a single continuous dimension, x. Ratio schedules are specified at one point of the continuum (x = 1) and interval schedules are specified at another point (x = 0). At all other values of x the specified interactive schedule requirements are a“blend” of ratio and interval schedule requirements, in which both the rate of reinforcement and the number of responses per reinforcer are dependent variables related to the rate of responding. The behavior of rats was observed with interactive schedules having four values for x between zero and unity inclusively. When x is greater than zero and less than unity a trade-off is specified in which an increase in the rate of responding increases the rate of reinforcement, but at a cost of increasing the number of responses per reinforcer required. Subjects responded at higher rates for values of x closer to unity (more ratio-like) and at lower rates for values of x closer to zero (more interval-like). Response rates were not proportional to reinforcement rates, nor did subject maximize the rate of reinforcement. Classes of models of behavior are discussed, and it is suggested that two-dimensional economic models which have as factors both reinforcement and response cost are most consistent with these data. It is further suggested that the interactive schedule may be a useful experimental tool in assessing such two-dimensional models because it can specify two-dimensional relationships between the dependent variables of reinforcement rate and response cost (number of responses per reinforcer) as functions of the rate of responding.