More on concurrent interval-ratio schedules: a replication and review.
Matching survives even when effort is equal, so schedule rates alone can sway choice.
01Research in Context
What this study did
Emmelkamp et al. (1986) ran pigeons on a new two-key schedule.
One key gave grain on a variable-time schedule, no peck needed.
The other key gave grain on a variable-ratio schedule, every few pecks.
Both keys took the same effort; only the grain rule differed.
The team asked: will birds still "match" time to grain rate, or will they "maximize" and pick the richer side?
What they found
Birds split their time almost exactly like the grain rates.
They did not throw all pecks at the ratio key to harvest more food.
Matching held even when response cost was the same on both keys.
The result says matching is not just a cheap way to save energy.
How this fits with other research
Glynn (1970) and Fantino (1969) already showed pigeons match on standard two-key setups. Emmelkamp et al. (1986) tighten the screw: they erase effort differences and still get matching, so the rule survives a harder test.
Reid et al. (1983) review says local grain rates push birds around. The new VT-VRT data land inside that picture; equal local rates kept choices even.
Macht (1971) found duration alone steers time. M’s grain rates did the same steering, showing two different knobs can drive the same allocation engine.
Why it matters
If your client stalls or hops between tasks, check the payoff rates, not just effort. Even when two responses cost the same, people (like pigeons) may still drift toward the richer schedule. To reduce bouncing, equalize the rate of good outcomes across choices, then watch time allocation settle.
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02At a glance
03Original abstract
It has been suggested that the failure to maximize reinforcement on concurrent variable-interval, variable-ratio schedules may be misleading. Inasmuch as response costs are not directly measured, it is possible that subjects are optimally balancing the benefits of reinforcement against the costs of responding. To evaluate this hypothesis, pigeons were tested in a procedure in which interval and ratio schedules had equal response costs. On a concurrent variable time (VT), variable ratio-time (VRT) schedule, the VT schedule runs throughout the session and the VRT schedule is controlled by responses to a changeover key that switches from one schedule to the other. Reinforcement is presented independent of response. This schedule retains the essential features of concurrent VI VR, but eliminates differential response costs for the two alternatives. It therefore also eliminates at least one significant ambiguity about the reinforcement maximizing performance. Pigeons did not maximize rate of reinforcement on this procedure. Instead, their times spent on the alternative schedules matched the relative rates of reinforcement, even when schedule parameters were such that matching earned the lowest possible overall rate of reinforcement. It was further shown that the observed matching was not a procedural artifact arising from the constraints built into the schedule.
Journal of the experimental analysis of behavior, 1986 · doi:10.1901/jeab.1986.46-331