Temporal control of periodic schedules: signal properties of reinforcement and blackout.
After long intervals, blackout shortens the post-reinforcement pause compared with food—watch for this omission effect in your schedules.
01Research in Context
What this study did
Researchers watched pigeons on fixed-interval schedules. They wanted to know what happens after food or after a blackout. Both events told the bird the next food would arrive in 60 or 180 seconds.
They measured how long the bird waited before pecking again. The key test was at the long 180-second interval.
What they found
After short waits, food and blackout gave the same pause. After long waits, blackout made the bird start sooner. Food made the bird wait longer.
This is the omission effect: the same future food time feels different when the last thing you saw was food versus darkness.
How this fits with other research
McSweeney et al. (1993) later showed pause length tracks the last interfood interval. Their linear-waiting rule adds math to the 1974 signal idea.
Dews (1966) already knew omitted food still keeps timing intact. The 1974 paper adds that the kind of signal, not just its absence, matters.
Lowe et al. (1977) found rats pause more than pigeons on the same schedules. Species and response style can change how the omission effect looks.
Why it matters
When you run long DRL or FI programs, the last stimulus can speed up or slow down the next response. If you give edible reinforcers, expect longer post-reinforcement pauses. If you use brief blackout or non-edible tokens, clients may restart sooner. Pick the signal that matches the pause you want.
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02At a glance
03Original abstract
Pigeons were exposed to periodic food-reinforcement schedules in which intervals ended with equal probability in either reinforcement or brief blackout. The effects on the pattern of key pecking of sequential probability of reinforcement, interval duration, and time to reinforcement opportunity were investigated in three experiments. The major results were: (1) at short absolute interval durations, time to reinforcement opportunity determined both postreinforcement and postblackout pause (time to first key peck within an interval); (2) at long intervals, postblackout pause was consistently shorter than postreinforcement pause, even if both events signalled the same time to the next reinforcement opportunity (omission effect); (3) when reinforcement and blackout signalled different times to the next reinforcement opportunity, within the same experiment, there was some evidence for interactions analogous to behavioral contrast.
Journal of the experimental analysis of behavior, 1974 · doi:10.1901/jeab.1974.22-535