Response rate viewed as engagement bouts: Effects of relative reinforcement and schedule type

The rate of a reinforced response is conceptualized as a composite of engag ement bouts (visits) and responding during visits. Part 1 of this paper des cribes a method fur estimating the rate of visit initiations and the averag e number of responses per visit from log survivor plots: the proportion of interresponse times (IRTs) longer than some elapsed time (log scale) plotte d as a function of elapsed time. In Part 2 the method is applied to IRT dis tributions from rats that obtained food pellets by nose poking a lighted ke y under various multiple schedules of reinforcement. As expected. total res ponse rate increased as a function of (a) increasing the rate of reinforcem ent (i.e., variable-interval [VI] 4 min vs. VI 1 min), (b) increasing the a mount of the reinforcer tone food pellet vs. four pellets), (c) increasing the percentage of reinforcers that were contingent on nose poking (25% vs. 100%, and (d) requiring additional responses after the end of the VI schedu le (i.e., adding a tandem variable-ratio [VR] 9 requirement). The first thr ee of these variables (relative reinforcement) increased the visit-initiati on rate. The tandem VR, in contrast, increased the number of responses per visit. Thus, variables that have similar effects on total response rate can be differentiated based on their effects on the components of response rat e.