Steady-state choice between four alternatives obeys the constant-ratio rule.
Stable four-choice concurrent VI schedules produce neat matching; rapid schedule changes do not.
01Research in Context
What this study did
Bensemann et al. (2015) let pigeons peck four keys. Each key paid off on its own VI schedule: 27, 9, 3, or 1. The birds stayed in this set-up until day-to-day response rates stopped changing.
The team then checked if the constant-ratio rule still held. That rule says choice ratios should match reinforcer ratios, even with four options.
What they found
The pigeons' pecks lined up with the constant-ratio rule. Birds distributed their responses in the same 27:9:3:1 proportions as the scheduled pay-offs.
Because the schedules stayed the same for many sessions, the birds had time to settle. Steady conditions let long-term reinforcement history drive choice, not momentary swings.
How this fits with other research
Bell et al. (2017) saw different results when the VI schedules flipped quickly. In that fast-changing set-up, pigeons did not follow the constant-ratio rule. The two studies seem to clash, but the gap is about speed: steady state lets the rule work; rapid change breaks it.
Older two-key studies like Burgess et al. (1971) and Hawkins (1979) showed that birds lock onto the richer side when pay-offs differ a lot. Bensemann et al. (2015) extends this idea to four keys and confirms the same lock-in pattern holds.
Najdowski et al. (2003) found that pigeons can shift choice almost overnight when delays change daily. Joshua's team shows that if you stop changing things, behavior locks in and follows simple ratio math.
Why it matters
When you run concurrent reinforcement programs, keep the contingencies stable long enough for learners to settle. If you want clean matching, avoid fiddling with schedules every day. Give the client time to show you their true preference, then use those data to adjust teaching or token ratios.
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02At a glance
03Original abstract
We investigated why violations to the constant-ratio rule, an assumption of the generalized matching law, occur in procedures that arrange frequent changes to reinforcer ratios. Our investigation produced steady-state data and compared them with data from equivalent, frequently changing procedures. Six pigeons responded in a four-alternative concurrent-schedule experiment with an arranged reinforcer-rate ratio of 27:9:3:1. The same four variable-interval schedules were used in every condition, for 50 sessions, and the physical location of each schedule was changed across conditions. The experiment was a steady-state version of a frequently changing procedure in which the locations of four VI schedules were changed every 10 reinforcers. We found that subjects' responding was consistent with the constant-ratio rule in the steady-state procedure. Additionally, local analyses showed that preference after reinforcement was towards the alternative that was likely to produce the next reinforcer, instead of being towards the just-reinforced alternative as in frequently changing procedures. This suggests that the effect of a reinforcer on preference is fundamentally different in rapidly changing and steady-state environments. Comparing this finding to the existing literature suggests that choice is more influenced by reinforcer-generated signals when the reinforcement contingencies often change.
Journal of the experimental analysis of behavior, 2015 · doi:10.1002/jeab.157