Cooperative responding in rats maintained by fixed‐ and variable‐ratio schedules
Variable ratio schedules keep partners cooperating longer and more evenly than fixed ratio.
01Research in Context
What this study did
The team placed pairs of rats in a shared cage. Each rat had to press its own lever.
Both rats earned food only when each completed its own fixed or variable ratio. The researchers compared FR 1, FR 10, and VR 10 schedules.
What they found
When the schedule changed from FR 1 to FR 10 or VR 10, the pairs worked together more often. VR 10 kept cooperation steady, while FR 10 created more pauses.
In short, intermittent ratio schedules boosted joint responding, and VR kept it smoother.
How this fits with other research
Van Houten et al. (1980) saw the same VR advantage in deaf students. Their tokens on VR kept attention high and disruption low, matching the steadier rat cooperation seen here.
Hawkins (1979) showed that when concurrent FR and VR differ a lot, animals pick the richer side. The 2018 study extends this idea: when both partners must finish their ratios, VR keeps both animals engaged instead of one quitting.
Fujita (1985) found VR schedules kept monkeys' discrimination accurate after learning. The rat study mirrors this: VR keeps joint behavior accurate and steady, not just fast.
Why it matters
If you run group contingencies in classrooms, clinics, or homes, switch from fixed to variable ratio after the skill is learned. VR keeps everyone working together with fewer post-reinforcement breaks. Try VR 5 next time you need steady partner work.
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02At a glance
03Original abstract
The present study investigated the effects of fixed-ratio (FR) and variable-ratio (VR) reinforcement schedules on patterns of cooperative responding in pairs of rats. Experiment 1 arranged FR 1, FR 10, and VR 10 schedules to establish cooperative responding (water delivery depended on the joint responding of two rats). Cooperative response rates and proportions were higher under intermittent schedules than under continuous reinforcement. The FR 10 schedule generated a break-and-run pattern, whereas the VR 10 schedule generated a relatively high and constant rate pattern. Experiment 2 evaluated the effects of parametric manipulations of FR and VR schedules on cooperative responding. Rates and proportions of cooperative responding generally increased between ratio sizes of 1 and 5 but showed no consistent trend as the ratio increased from 5 to 10. Experiment 3 contrasted cooperative responding between an FR6 schedule and a yoked control schedule. Coordinated behavior occurred at a higher rate under the former schedule. The present study showed that external consequences and the schedules under which the delivery of these consequences are based, select patterns of coordinated behavior.
Journal of the Experimental Analysis of Behavior, 2018 · doi:10.1002/jeab.457