Catania, A. C., & Reynolds, G. S. (1968).
A quantitative analysis of the responding maintained by interval schedules of reinforcement.
Journal of the Experimental Analysis of Behavior,
11, 327-383.
Interval schedules of reinforcement maintained pigeons' key-
pecking in six experiments. Each schedule was specified in terms
of mean interval, which determined the maximum rate of
reinforcement possible, and distribution of intervals, which
ranged from many-valued (variable-interval) to single-valued
(fixed-interval). In Exp. 1, the relative durations of a sequence
of intervals from an arithmetic progression were held constant
while the mean interval was varied. Rate of responding was a
monotonically increasing, negatively accelerated function of rate
of reinforcement over a range from 8.4 to 300
reinforcements per hour. The rate of responding also increased as
time passed within the individual intervals of a given schedule.
In Exp. 2 and 3, several variable-interval schedules made up of
different sequences of intervals were examined. In each schedule,
the rate of responding at a particular time within an interval
was shown to depend at least in part on the local rate of
reinforcement at that time, derived from a measure of the
probability of reinforcement at that time and the proximity of
potential reinforcements at other times. The functional
relationship between rate of responding and rate of reinforcement
at different times within the intervals of a single schedule was
similar to that obtained across different schedules in Exp. 1.
Experiments 4, 5 and 6 examined fixed-interval and two-valued
(mixed fixed-interval fixed-interval) schedules, and demonstrated
that reinforcement at one time in an interval had substantial
effects on responding maintained at other times. It was concluded
that the rate of responding maintained by a given interval
schedule depends not on the overall rate of reinforcement
provided but rather on the summation of different local effects
of reinforcement at different times within intervals.