Residence time and choice in concurrent foraging schedules.
Pigeons hang longer in the patch that pays faster, yet still fall short of the best payoff — plan for this slight undermatching in human concurrent schedules.
01Research in Context
What this study did
Ghaziuddin et al. (1996) watched pigeons choose between two feeding spots.
Each spot gave grain at a different speed.
The birds could hop between spots whenever they wanted.
What they found
Birds stayed longer where grain came faster.
They still did not move enough to get the most food possible.
This gap is called undermatching.
How this fits with other research
PLISKOFF (1963) first showed perfect matching: pecks lined up exactly with payoff rate.
Hopkins et al. (1977) later re-checked old data and found the same undermatching M saw.
Friedling et al. (1979) showed undermatching fades after six sessions, hinting history matters.
Together the papers say: animals rarely maximize; they get close and then stop.
Why it matters
When you set up two tasks for a client, expect them to split time a bit shy of the richer one.
Do not chase perfect 100% allocation; watch for steady, slightly flat preference instead.
Use at least a week per condition so old history can wash out.
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Join Free →Give two tasks with 3:1 reinforcer rates, then look for about a 2.5:1 time split — tweak only if it drifts wider.
02At a glance
03Original abstract
Five pigeons were trained on a concurrent-schedule analogue of the "some patches are empty" procedure. Two concurrently available alternatives were arranged on a single response key and were signaled by red and green keylights. A subject could travel between these alternatives by responding on a second yellow "switching" key. Following a changeover to a patch, there was a probability (p) that a single reinforcer would be available on that alternative for a response after a time determined by the value of lambda, a probability of reinforcement per second. The overall scheduling of reinforcers on the two alternatives was arranged nonindependently, and the available alternative was switched after each reinforcer. In Part 1 of the experiment, the probabilities of reinforcement, rho(red) and rho(green), were equal on the two alternatives, and the arranged arrival rates of reinforcers, lambda(red) and lambda(green), were varied across conditions. In Part 2, the reinforcer arrival times were arranged to be equal, and the reinforcer probabilities were varied across conditions. In Part 3, both parameters were varied. The results replicated those seen in studies that have investigated time allocation in a single patch: Both response and time allocation to an alternative increased with decreasing values of lambda and with increasing values of rho, and residence times were consistently greater than those that would maximize obtained reinforcer rates. Furthermore, both response- and time-allocation ratios undermatched mean reinforcer-arrival time and reinforcer-frequency ratios.
Journal of the experimental analysis of behavior, 1996 · doi:10.1901/jeab.1996.65-423