Reinforcement magnitude and pausing on progressive-ratio schedules.
Pausing after reinforcement is driven by both the size of the last reward and the signal of what comes next.
01Research in Context
What this study did
Pigeons worked on a progressive-ratio schedule. The required number of pecks went up after each food delivery.
The team changed two things. They gave either one pellet or four pellets. They also turned on a red or green light that told the bird what the next ratio would be.
The goal was to see how these two signals together affect the pause right after food.
What they found
Longer ratio requirements produced longer pauses. That part was expected.
Big news: pause length was set by both the last reward size and the upcoming light cue. Neither factor ruled alone.
A small reward plus a bad-news light made the bird wait the longest. A big reward plus a good-news light made the bird start again fastest.
How this fits with other research
Kodera et al. (1976) first showed that brief cues can control pausing. Yuwiler et al. (1992) now add that the cue must be paired with reward size to matter.
Brinker et al. (1975) proved that past reinforcement becomes its own signal. The new study keeps that idea but shows the next signal is just as powerful.
Langford et al. (2021) gave birds an anxiety drug that cut pausing only when rich rewards turned lean. Their drug probe and the 1992 magnitude probe both point to the same rule: pausing is strongest when conditions are about to get worse.
Why it matters
Your client may stop working after a big reinforcer. Check what signal you just gave about the next task. A small candy plus a hard demand coming up can create a long pause. Swap the signal or add more value to calm the pause. You now have two levers, not one.
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02At a glance
03Original abstract
Rats responded under progressive-ratio schedules for sweetened milk reinforcers; each session ended when responding ceased for 10 min. Experiment 1 varied the concentration of milk and the duration of postreinforcement timeouts. Postreinforcement pausing increased as a positively accelerated function of the size of the ratio, and the rate of increase was reduced as a function of concentration and by timeouts of 10 s or longer. Experiment 2 varied reinforcement magnitude within sessions (number of dipper operations per reinforcer) in conjunction with stimuli correlated with the upcoming magnitude. In the absence of discriminative stimuli, pausing was longer following a large reinforcer than following a small one. Pauses were reduced by a stimulus signaling a large upcoming reinforcer, particularly at the highest ratios, and the animals tended to quit responding when the past reinforcer was large and the stimulus signaled that the next one would be small. Results of both experiments revealed parallels between responding under progressive-ratio schedules and other schedules containing ratio contingencies. Relationships between pausing and magnitude suggest that ratio pausing is under the joint control of inhibitory properties of the past reinforcer and excitatory properties of stimuli correlated with the upcoming reinforcer, rather than under the exclusive control of either factor alone.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.58-377