Reinforcement and punishment effects in concurrent schedules: A test of two models.
Equal punishment on both keys makes pigeons favor the richer key more, backing a simple subtractive model.
01Research in Context
What this study did
Hammond (1980) ran three lab tests with pigeons. The birds pecked two keys for food on concurrent VI schedules.
Punishment followed every peck on both keys. The team asked which math model predicted the new choice split.
What they found
When mild punishment hit both sides equally, birds leaned even more toward the richer key. Only the subtractive model forecast this extra tilt.
The other model missed the mark. Data showed punishment simply lowers the value of each key, not special new rules.
How this fits with other research
de Villiers (1980) is a direct replication. Same year, same birds, same result: subtractive wins.
Delini-Stula (1970) looked like a clash at first. It found punished response rates rising when the alternate side paid more. But that study used multiple schedules, not concurrent. Different layout, different story — no real fight.
Landon et al. (2002) later dropped punishment and still saw choice drift with reinforcer ratios. They extended the method to show both quick and slow effects of reinforcement history.
Why it matters
If you add a mild punisher to both options — say, a brief verbal “no” or response cost — expect the learner to favor the richer side even more. Track baseline choice first, apply equal consequences, then watch for the subtractive shift. This gives you a clean, math-based way to predict, not just guess, how punishment reshapes preference.
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Join Free →Plot baseline choice between two VI options, apply the same mild punisher to both, and check if richer-side preference grows.
02At a glance
03Original abstract
The joint effects of punishment and reinforcement on the pigeon's key-peck response were examined in three choice experiments conducted to compare predictions of Farley and Fantino's (1978) subtractive model with those made by Deluty's (1976) and Deluty and Church's (1978) model of punishment. In Experiment 1, the addition of equal punishment schedules to both alternatives of a concurrent reinforcement schedule enhanced the preference exhibited for the more frequent reinforcement alternative. Experiment 2 demonstrated decreases in the absolute response rate for each member of a concurrent reinforcement schedule when increasing frequencies of punishment were added to each alternative. Experiment 3 found that preference for the denser of two reinforcement schedules diminished when the absolute frequencies of reinforcement were increased by a constant factor and conditions of punishment for both alternatives were held constant. Diminished preferences were obtained regardless of whether the frequency of punishment associated with the denser reinforcement schedule was greater or less than that associated with the lean reinforcement alternative. The results from all three experiments uniquely supported Farley and Fantino's (1978) subtractive model of punishment and reinforcement.
Journal of the experimental analysis of behavior, 1980 · doi:10.1901/jeab.1980.33-311