Davison, M., & Baum, W. M. (2003).
Every reinforcer counts: Reinforcer magnitude and local preference.
Journal of the Experimental Analysis of Behavior,
80, 95-129.
Six pigeons were trained on concurrent variable-interval
schedules. Sessions consisted of seven components, each lasting
10 reinforcers, with the conditions of reinforcement differing
between components. The component sequence was randomly selected
without replacement. In Experiment 1, the concurrent-schedule
reinforcer ratios in components were all equal to 1.0, but across
components reinforcer-magnitude ratios varied from 1:7 through
7:1. Three different overall reinforcer rates were arranged
across conditions. In Experiment 2, the reinforcer-rate ratios
varied across components from 27:1 to 1:27, and the
reinforcer-magnitude ratios for each alternative were changed
across conditions from 1:7 to 7:1. The results of Experiment 1
replicated the results for changing reinforcer-rate ratios across
components reported by Davison and Baum (2000, 2002): Sensitivity
to reinforcer-magnitude ratios increased with increasing numbers
of reinforcers in components. Sensitivity to magnitude ratio,
however, fell short of sensitivity to reinforcer-rate ratio. The
degree of carryover from component to component depended on the
reinforcer rate. Larger reinforcers produced larger and longer
postreinforcer preference pulses than did smaller reinforcers.
Similar results were found in Experiment 2, except that
sensitivity to reinforcer magnitude was considerably higher and
was greater for magnitudes that differed more from one another.
Visit durations following reinforcers measured either as number
of responses emitted or time spent responding before a changeover
were longer following larger than following smaller reinforcers,
and were longer following sequences of same reinforcers than
following other sequences. The results add to the growing body of
research that informs model building at local levels.
Key words: choice, generalized matching, local analyses,
preference pulses, pecking, pigeons