Choice with a fixed requirement for food, and the generality of the matching relation.
Fixed-ratio or fixed-interval setups with equal requirements can shatter the matching law, so measure choice directly instead of predicting it.
01Research in Context
What this study did
Researchers watched 11 pigeons choose between two keys. Each key needed the same fixed number of pecks or the same fixed wait time to deliver food.
The birds could switch keys at any moment. The team logged every peck to see if the classic matching law still held when the food requirement stayed locked.
What they found
Matching often fell apart. Birds spread their time unevenly even though both sides asked for identical work.
Efficiency stayed high anyway. The pigeons still collected their food with little extra effort, so the break in matching did not hurt them.
How this fits with other research
Palya (1992) saw smooth, graded choices between fixed-interval schedules. The new data look opposite, but the tasks differ. L let the ratio between intervals change; A et al. kept the requirement fixed on both keys.
Aragona et al. (1975) showed that added response rules can wipe out normal choice patterns. Both papers warn that small procedural tweaks can override the matching relation.
Carr et al. (2002) found that pigeons quickly drop old patterns when food odds shift. Their rapid switch supports the idea that fixed requirements, not history, drive the present result.
Why it matters
If you run concurrent schedules with equal response requirements, do not assume matching will appear. Check the actual allocation; you may need extra prompts or different ratios to get the distribution you want.
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Plot your client’s time allocation across equal-work options; if it strays from the programmed reinforcer ratio, adjust the requirement or add discriminative stimuli.
02At a glance
03Original abstract
Pigeons were trained on choice procedures in which responses on each of two keys were reinforced probabilistically, but only after a schedule requirement had been met. Under one arrangement, a fixed-interval choice procedure was used in which responses were not reinforced until the interval was over; then a response on one key would be reinforced, with the effective key changing irregularly from interval to interval. Under a second, fixed-ratio choice procedure, responses on either key counted towards completion of the ratio and then, once the ratio had been completed, a response on the probabilistically selected key would produce food. In one experiment, the schedule requirements were varied for both fixed-interval and fixed-ratio schedules. In the second experiment, relative reinforcement rate was varied. And in a third experiment, the duration of an intertrial interval separating choices was varied. The results for 11 pigeons across all three experiments indicate that there were often large deviations between relative response rates and relative reinforcement rates. Overall performance measures were characterized by a great deal of variability across conditions. More detailed measures of choice across the schedule requirement were also quite variable across conditions. In spite of this variability, performance was consistent across conditions in its efficiency of producing food. The absence of matching of behavior allocation to reinforcement rate indicates an important difference between the present procedures and other choice procedures; that difference raises questions about the specific conditions that lead to matching as an outcome.
Journal of the experimental analysis of behavior, 1986 · doi:10.1901/jeab.1986.45-333