The effects of different component response requirements in multiple and concurrent schedules.
Key pecks outrank lever presses even when pay is equal—bake this bias into matching-law graphs.
01Research in Context
What this study did
Researchers put pigeons in a box with two choices. One choice needed a key peck. The other needed a lever press.
Both choices paid off at the same rate. The team watched which choice the birds picked more often.
They ran this test under two set-ups: multiple schedules and concurrent schedules.
What they found
Birds pecked the key far more than they pressed the lever. Even when both paid the same, key pecks won.
The old matching law still worked, but only if you added a bias term for key pecking.
How this fits with other research
Davis et al. (1972) showed key pecks follow matching law when extra food is added. Bradshaw et al. (1978) now shows the same law needs a bias tweak when key pecks compete with lever presses.
Rose et al. (2000) found that sweeter water shifts the top rate (k) in lever-press tasks. Bradshaw et al. (1978) shows that response type also shifts the rate, so both reinforcer size and response form change the curve.
Lowe et al. (1995) proved that harder lever presses slow rats down. Bradshaw et al. (1978) adds that even easy lever presses lose to key pecks, showing response form matters as much as force.
Why it matters
When you run concurrent schedules, do not assume all responses are equal. If one option is a key peck and the other is a lever press, expect a built-in bias toward pecking. Add that bias into your matching-law calculations or your data will look off.
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02At a glance
03Original abstract
Six pigeons were trained on multiple and concurrent schedules. The reinforcement rates were varied systematically (a) when lever pressing was required in one component and key pecking in the successive component; (b) when lever pressing was required in both multiple components; (c) when key pecking was required in both multiple components; and (d) when key pecking was required on one schedule and lever pressing was required on the concurrently-available schedule. Only the absolute level of responding was changed by different response requirements. Analyzed by the generalized matching law, performance under different response requirements resulted in a bias toward key pecking, and the measured response bias was the same in multiple and concurrent schedule arrangements. The bias in time measures obtained from concurrent schedule performance was reliably smaller than the obtained response biases. The sensitivity to reinforcement-rate changes was ordered: concurrent key-lever; multiple key-key; multiple lever-key; and, the least sensitive, multiple lever-lever. The results confirm that requirements of different topographical responses can be handled by the generalized matching law mainly in the bias parameter, but problems for this type of analysis may be caused by the changing sensitivity to reinforcement in multiple schedule performance as response requirements are changed.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.29-283