Behavioural Processes, 12 (1986) 273-285 Elsevier 273 SIMPLE AND MULTIPLE SCHEDULE RESPONDING AND BEHAVIORAL CONTRAST WHEN PIGEONS PRESS TREADLES* FRANCES K. MCSWEENEYl, JAMES D. DOUGAN AND VALERI A. FARMER3 1Dept. of Psychology, Washington State University, Pullman, WA 2 Present address: Dept. of Psychology, Indiana University, Bloomington, IN 3Present address: Dept. of Psychology, University of Massachusetts, Amherst, MA (Accepted 22 August 1985) ABSTRACT McSweeney, F. K., Dougan, J. D. and Farmer, V. A. 1985. Simple and multiple schedule responding and behavioral contrast when pigeons press treadles. Behav. Processes 12: 273-285. Positive behavioral contrast has been observed when pigeons press treadles on multiple schedules for high rates of reinforcement, but not for low rates. Negative treadle-press contrast has been observed for low rates of reinforcement. Two experiments showed that differences between response rates emitted during simple and multiple schedules appear and fail to appear under similar conditions. The experiments showed that the rate of pressing during the less favorable component of a multiple schedule was less than the rate of pressing during a comparable simple schedule (negative contrast). The rate of treadle-pressing during the more favorable component was not greater than the rate of pressing during a comparable simple schedule, when the schedules provided a low rate of reinforcement (absence of positive contrast), but it was when the schedules provided a high rate of reinforcement (positive contrast). These results help to clarify the definition of behavioral contrast by showing that simple schedules may be appropriate baselines from which to define and measure contrast. ---------- *Reprints may be obtained from Dr. Frances K. McSweeney. Some of these data were presented at the 1983 meeting of the Psychonomic Society. The authors wish to thank Dr. John Hinson for his helpful comments on an earlier version of this paper. 0376-6357/86/$03.50 @ 1986 Elsevier Science Publishers B.V. (Biomedical Division)