Testing a stochastic foraging model in an operant simulation: Agreement with qualitative but not quantitative predictions.
Pigeons stay too long in empty patches, showing that animals rely on simple rules, not perfect economics.
01Research in Context
What this study did
Researchers set up an operant chamber like a video game for pigeons. The birds pecked keys to earn grain in two patches. One patch always gave food on the same schedule. The other patch sometimes ran out.
The team tracked when the birds switched patches. They compared the moves to a math model that predicts the best time to leave. The model comes from biology, not behavior analysis.
What they found
The pigeons got the big picture right. They left a patch more often when it was empty. But they stayed too long in dry patches and checked them again too soon.
The numbers did not fit the model. The birds over-sampled empty spots. They acted like something besides pure payoff guided their choices.
How this fits with other research
Bachman et al. (1988) saw a similar mismatch. Their pigeons also violated strict optimality rules when search time changed. Both labs show that animals use rules of thumb, not perfect math.
Grosch et al. (1981) and Cullinan et al. (2001) found that adding a signal during a delay keeps pigeons loyal to one key. The foraging study had no signals, so the birds kept sampling. The papers together say: when cues are weak, animals explore more.
Lattal (1984) showed that blackout signals protect response rates during delays. The foraging task had no such signals, perhaps why birds re-checked empty patches. The gap suggests signaling could tighten patch choices.
Why it matters
Your clients also over-explore when the payoff rules are unclear. If a task suddenly stops producing reinforcement, learners may keep trying or return after a break. Add clear signals — a timer, a color change, a countdown — to mark when reinforcement is no longer available. This can cut wasted responses and speed up the shift to a new task or location.
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02At a glance
03Original abstract
An operant simulation of foraging through baited and empty patches was studied with 4 pigeons. On a three-key panel, side keys were designated as patches, and successive opportunities to complete 16 fixed-ratio 10 schedules on side keys were defined as encounters with feeders. In a random half of the patches in any session, some of the fixed-ratio 10 schedules yielded reinforcement (baited feeders) and the other schedules yielded nonreinforcement (empty feeders). In the other half of the patches, all feeders were empty. Pigeons could travel between patches at any time by completing a fixed-ratio schedule on the center key. An optimal foraging model was tested in Experiments 1 and 2 by varying center-key travel time and number of baited feeders in baited patches. The ordinal predictions that number of feeders visited in empty patches would increase with travel time and decrease as number of baited feeders increased were supported, but pigeons visited far more feeders in empty patches than the optimal number predicted by the model to maximize energy/time. In Experiment 3, evidence was found to suggest that the number of empty feeders encountered before the first baited feeder in baited patches is an important factor controlling leaving empty patches.
Journal of the experimental analysis of behavior, 1993 · doi:10.1901/jeab.1993.59-323