Green, L., & Holt, D. D. (2003).
Economic and biological influences on key pecking and treadle pressing in pigeons.
Journal of the Experimental Analysis of Behavior,
80, 43-58.
Pigeons were studied on a two-component multiple schedule in
which the required operant was, in different conditions,
biologically relevant (i.e., key pecking) or nonbiologically
relevant (i.e., treadle pressing). Responding was reinforced on a
variable-interval (VI) 2-min schedule in both components. In
separate phases, additional food was delivered on a variable-time
(VT) 15-s schedule (response independent) or a VI 15-s schedule
(response dependent) in one of the components. The addition of
response-independent food had different effects on responding
depending on the operant response and on the frequency with which
the components alternated. When components alternated frequently
(every 10 s), all pigeons keypecked at a much higher rate during
the component with the additional food deliveries, whether
response dependent or independent. In comparison, treadle
pressing was elevated only when the additional food was response
dependent; rate of treadling was lower when the additional food
was response independent. When components alternated infrequently
(every 20 min), pigeons key pecked at high rates at points of
transition into the component with the additional food
deliveries. Rate of key pecking decreased with time spent in the
20-min component when the additional food was response
independent, whereas rate of pecking remained elevated in that
component when the additional food was response dependent. Under
otherwise identical test conditions, rate of treadle pressing
varied only as a function of its relative rate of
response-dependent reinforcement. Delivery of
response-independent food thus had different, but predictable,
effects on responding depending on which operant was being
studied, suggesting that animal-learning procedures can be
integrated with biological considerations without the need to
propose constraints that limit general laws of learning.
Key words: biological effect, economic effect, contingent
reinforcement, multiple