Changing the response unit from a single peck to a fixed number of pecks in fixed-interval schedules.
Reinforcement schedule structure (not just response rate) controls post-reinforcement pausing in pigeons.
01Research in Context
What this study did
Fixsen et al. (1972) worked with pigeons on fixed-interval schedules. The birds had to peck a key for food.
The twist: instead of counting every single peck, the team made the birds peck five times in a row. Only the fifth peck started the timer for the next interval.
They watched how this small rule change altered the birds’ pausing after food.
What they found
The birds still paused after food, then ran faster as the interval closed. That familiar pattern stayed.
The pause grew a little longer when five-peck units were required. Schedule structure, not just speed, steered the pause.
How this fits with other research
Nevin (1967) had already shown that changing interval schedules alters response probability while leaving discrimination intact. The 1972 study narrows the focus to post-reinforcement pausing and finds the same theme: schedule rules, not response form, drive the pattern.
LANE et al. (1963) showed that switching from continuous to variable-interval reinforcement changes vocal pitch and duration. Together, these papers say schedule structure can reshape any part of a response — timing, force, or acoustics.
Branch (1977) used second-order chained schedules like the 1972 team, but asked what happens when food omission is signalled. Both studies reveal that the way we stitch schedule parts together controls behavior far more than the exact response topography.
Why it matters
For BCBAs, the lesson is to look past response counts and watch how the schedule itself is built. If you want a learner to pause longer after reinforcement, cluster responses into small fixed-ratio units inside your interval program. Try asking for three touches, not one, before the next interval starts. The pause will lengthen without extra prompts or tokens.
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Join Free →Program three-response clusters at the start of each interval and watch the post-reinforcement pause stretch.
02At a glance
03Original abstract
Each of three pigeons was studied first under a standard fixed-interval schedule. With the fixed interval held constant, the schedule was changed to a second-order schedule in which the response unit was the behavior on a small fixed-ratio schedule (first a fixed-ratio 10 and then a fixed-ratio 20 schedule). That is, every completion of the fixed-ratio schedule produced a 0.7-sec darkening of the key and reset the response count to zero for the next ratio. The first fixed-ratio completed after the fixed-interval schedule elapsed produced the 0.7-sec blackout followed immediately by food. These manipulations were carried out under two different fixed-interval durations for each bird ranging from 3 min to 12 min. The standard fixed-interval schedules produced the typical pause after reinforcement followed by responding at a moderate rate until the next reinforcement. The second-order schedules also engendered a pause after reinforcement, but responding occurred in bursts separated by brief pauses after each blackout. For a particular fixed-interval duration, post-reinforcement pauses increased slightly as the number of pecks in the response unit increased despite large differences in the rate and pattern of key pecking. Post-reinforcement pause increased with the fixed-interval duration under all response units. These data confirm that the allocation of time between pausing and responding is relatively independent of the rate and topography of responding after the pause.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.17-193