TITRATION OF SCHEDULE PARAMETERS BY PIGEONS¹

Abstract

Pigeons were tested in a computer-controlled two-key chamber. A standard (nonchanging) schedule of reinforcement was in force on one key, and an adjusting schedule on the other. The schedules were available concurrently after each reinforcement, but after the first peck on either key (the choice peck), the schedule on the other key was made inoperative. The parameter of the adjusting schedule was decreased when the standard schedule was chosen and increased when the adjusting schedule was chosen. The standard schedule was changed only between sessions. Fixed intervals and fixed ratios were used as standard schedules, and intervals and ratios were used as adjusting schedules. When standard and adjusting schedules were of the same type, median parameters on the adjusting key equalled those of the standard schedules, at four values of each standard schedule. For four of five birds, and for the group median, similar curves could be plotted through the indifference points obtained from a standard ratio with an adjusting interval, and from a standard interval with an adjusting ratio. These points showed consistent individual differences, but they could be predicted by assuming that the median time from the choice peck to reinforcement should be the same on both keys. This is equivalent to treating the schedule as a concurrent chain and assuming that Herrnstein's quantitative law of effect applies.

Choice: A Local Analysis

“…This process can account for maximization on concurrent VR schedules and for matching on concurrent VI schedules. In addition, it is consistent with a number of procedures explicitly designed to discriminate between melioration and global maximization (Boelens, 1984;Herrnstein & Vaughan, 1980;Vaughan, 1981;Vaughan, Kardish, & Wilson, 1982; also see Herrnstein & Heyman, 1979;Lea, 1976;Mazur, 1981).…”

Adaptive Behavior and Learning

“…This situation is equivalent to an operantconditioning experiment in which the rate of return for responding to one alternative decreases with time, while the rate of return to be expected from another alternative (i.e., other patches, in the natural case) remains constant. An example might be a two-choice procedure: On one response key a ratio schedule where the size of the ratio increases with each food delivery and on the other a constant ratio schedule, the decreasing ratio would be reset to its initial value after each switch to the constant ratio (Hodos & Trumbule, 1967;Lea, 1976). Obviously, the optimal course is for the predator to leave a patch when the 'instantaneous rate of return drops below the rate of return from the habitat as a whole.…”

Recent Reinforcement‐schedule Research and Applied Behavior Analysis

“…The last schedule described by Ferster and Skinner (1957) was an adjusting schedule in which the response requirement of a ratio schedule was increased or decreased after each reinforcer as a function of how long the animal paused before responding after each reinforcement. These adjusting procedures sometimes have been described as titration procedures (e.g., Lea, 1976;Weiss & Laties, 1959). Hackenberg and Axtell (1993) used an interactive dynamic reinforcement schedule to study the control of human behavior by longand short-term consequences.…”