McSweeney, F. K., Weatherly, J. N., & Swindell, S. (1996).
Within-session changes in responding during concurrent variable-interval schedules.
Journal of the Experimental Analysis of Behavior,
66, 75-95.
Five rats and 4 pigeons responded for food delivered by several
concurrent variable-interval schedules. The sum of the rates of
reinforcement programmed for the two components varied from 15 to
480 reinforcers per hour in different conditions. Rates of
responding usually changed within the experimental session in a
similar manner for the two components of each concurrent
schedule. The within-session changes were similar to previously
reported changes during simple schedules that provided rates of
reinforcement equal to the sum of all reinforcers obtained from
the concurrent schedules. The number of changeovers also changed
within sessions in a manner similar to the changes in
instrumental responding. These results suggest that changeovers
are governed by the same variables that govern instrumental
responding. They also suggest that the within-session change in
responding during each component of a concurrent schedule is
determined by approximately the sum of the reinforcers obtained
from both components when both components provide the same type
of reinforcer.
Key words: within-session patterns, concurrent schedule, matching
law, variable-interval schedule, changeovers, key peck, lever
press, rats, pigeons