Landon, J., Davison, M., & Elliffe, D. (2003).
Concurrent schedules: Reinforcer magnitude effects.
Journal of the Experimental Analysis of Behavior,
79, 351-365.
Five pigeons were trained on pairs of concurrent
variable-interval schedules in a switching-key procedure. The
arranged overall rate of reinforcement was constant in all
conditions, and the reinforcer-magnitude ratios obtained from the
two alternatives were varied over five levels. Each condition
remained in effect for 65 sessions and the last 50 sessions of
data from each condition were analyzed. At a molar level of
analysis, preference was described well by a version of the
generalized matching law, consistent with previous reports. More
local analyses showed that recently obtained reinforcers had
small measurable effects on current preference, with the most
recently obtained reinforcer having a substantially larger
effect. Larger reinforcers resulted in larger and longer
preference pulses, and a small preference was maintained for the
larger-magnitude alternative even after long interreinforcer
intervals. These results are consistent with the notion that the
variables controlling choice have both short- and long-term
effects. Moreover, they suggest that control by reinforcer
magnitude is exerted in a manner similar to control by reinforcer
frequency. Lower sensitivities when reinforcer magnitude is
varied are likely to be due to equal frequencies of different
sized preference pulses, whereas higher sensitivities when
reinforcer rates are varied might result from changes in the
frequencies of different sized preference pulses.
Key words: concurrent schedules, choice, generalized matching, reinforcer magnitude, key peck, pigeons