Temporal control on interval schedules: what determines the postreinforcement pause?
The postreinforcement pause copies the length of the prior interfood interval, so the last cycle sets the wait time for the next.
01Research in Context
What this study did
McSweeney et al. (1993) worked with pigeons on fixed-interval schedules. They asked what sets the length of the postreinforcement pause. Is it the time that just passed, the time still to come, or both?
The team varied the prior interfood interval while keeping the upcoming FI the same. They watched how long the bird waited before starting to peck again.
What they found
The pause tracked the preceding interfood interval almost perfectly. Longer waits after food made the next pause longer. This fits the linear waiting rule: wait time equals a fixed slice of the last cycle.
Small extra cues still mattered, but the prior interval was the main driver.
How this fits with other research
DeVellis et al. (1979) had earlier said the pause follows a power law: double the FI, multiply the pause by a constant factor. McSweeney et al. (1993) do not reject that math; they show the bird uses the last interval as the input. The two rules work together, one inside the other.
Catania et al. (1974) showed that blackout signals can shorten pauses when they tell the bird food is far away. K et al. confirm the prior interval is key, but their data still leave room for these signaled adjustments.
Bauman et al. (1996) later used progressive-interval schedules and saw pauses grow step-by-step. Their result is a direct extension: the same linear waiting rule holds when the interval keeps changing.
Why it matters
When you run FI schedules with a client, remember the last interval sets the next wait. If you stretch the interval too fast, the pause may stretch just as fast and kill momentum. Keep steps small and let the prior success set the clock.
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Join Free →Record the actual time between reinforcers in your current FI program; if you increase the FI next week, raise it in small, steady steps so the pause grows gently with the history the learner already has.
02At a glance
03Original abstract
On fixed-interval or response-initiated delay schedules of reinforcement, the average pause following food presentation is proportional to the interfood interval. Moreover, when a number of intervals of different durations occur in a programmed cyclic series, postreinforcement pauses track the changes in interval value. What controls the duration of postreinforcement pauses under these conditions? Staddon, Wynne, and Higa (1991), in their linear waiting model, propose control by the preceding interfood interval. Another possibility is that delay to reinforcement, signaled by a key peck and/or stimulus change, determines the subsequent pause. The experiments reported here examined the role of these two possible time markers by studying the performance of pigeons under a chained cyclic fixed-interval procedure. The data support the linear waiting model, but suggest that more than the immediately preceding interfood interval plays a role in temporal control.
Journal of the experimental analysis of behavior, 1993 · doi:10.1901/jeab.1993.60-293