Patch choice as a function of procurement cost and encounter rate.
When low-effort reinforcement is rare, animals choose fewer but bigger pay-offs instead of working harder.
01Research in Context
What this study did
Researchers let rats pick between two food patches. One patch needed few lever presses. The other needed many.
They then made the easy patch rare. They watched how meal size and daily visits changed.
What they found
Rats still chose the low-cost patch even when it was hard to find. They did not switch to the high-cost patch.
Instead they ate fewer but bigger meals. Daily foraging cost stayed the same.
How this fits with other research
Saunders et al. (1988) showed animals treat cost per gram as a single price. Sutphin et al. (1998) adds place: rats shop for the cheapest patch the way shoppers hunt sales.
Dixon et al. (2016) later showed the rule works with people. When money felt scarce, gamblers took bigger delayed rewards, mirroring the rats' bigger meals.
Haemmerlie (1983) used concurrent-chain schedules and found choice flips when terminal links change. Sutphin et al. (1998) flips the lens: patch encounter rate, not link length, drives the choice.
Why it matters
For your clients, response effort is a hidden patch cost. If the easy way to earn tokens, praise, or breaks is scarce, the client may still wait for it rather than work harder. You can honor this by giving fewer but richer reinforcement windows instead of loading on extra work. Watch total daily effort, not just how often you deliver.
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02At a glance
03Original abstract
The effects of patch encounter rate on patch choice and meal patterns were studied in rats foraging in a laboratory environment offering two patch types that were encountered sequentially and randomly. The cost of procuring access to one patch was greater than the other. Patches were either encountered equally often or the high-cost patch was encountered more frequently. As expected, rats exploited the low-cost patch on almost 100% of encounters and exploited the high-cost patch on a percentage of encounters that was inversely proportional to its cost. Meal size was the same at both patches. Surprisingly, when low-cost patches were rare, the rats did not increase their use of high-cost patches. This resulted in spending more time and energy searching for patches and a higher average cost per meal. The rats responded to this increased cost by reducing the frequency and increasing the size of meals at both patches and thereby limited total daily foraging cost and conserved total intake.
Journal of the experimental analysis of behavior, 1998 · doi:10.1901/jeab.1998.69-5