BIASING THE PACEMAKER IN THE BEHAVIORAL-THEORY OF TIMING

In the behavioral theory of tinting, pacemaker rate is determined by o verall rate of reinforcement. A two-alternative free-operant psychophy sical procedure was employed to investigate whether pacemaker period w as also sensitive to the differential rate of reinforcement. Respondin g on a left key during the first 25 s and on a right key during the se cond 25 s of a 50-s trial was reinforced at variable intervals, and va riable-interval schedule values during the two halves of the trials we re varied systematically Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Es timates of pacemaker period were derived from fits of a function predi cted by the behavioral theory of timing to right-key response proporti ons in consecutive 5-s bins of the 50-s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strong ly favored right-key responses, and were longest when the differential reinforcer rate most strongly favored left-key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.