Bauman, R. A., Raslear, T. G., Hursh, S. R., Shurtleff, D., & Simmons, L. (1996).
Substitution and caloric regulation in a closed economy.
Journal of the Experimental Analysis of Behavior,
65, 401-422.
Three experiments were conducted to study the effect of an
imperfect substitute for food on demand for food in a closed
economy. In Experiments 1 and 2, rats pressed a lever for their
entire daily food ration, and a fixed ratio of presses was
required for each food pellet. In both experiments, the fixed
ratio was held constant during a daily session but was increased
between sessions. The fixed ratio was increased over a series of
daily sessions once in the absence of concurrently available
sucrose and again when sucrose pellets were freely available. For
both series, increases in the fixed ratio reduced food intake,
but body weight was reduced only in the no-sucrose condition. In
the sucrose condition, body weight and total caloric intake
(sucrose plus food) were relatively unaffected by increases in
the fixed ratio. At all fixed ratios, food intake was
proportionally reduced by the intake of sucrose. In Experiment 3,
monkeys obtained food or saccharin by pressing keys; the fixed
ratio of presses per food pellet was increased once when tap
water was each monkey's only source of fluid, again when each
monkey's water was sweetened with saccharin, and a third time
when each monkey had concurrent access to the saccharin solution
and plain water. Increases in the fixed ratio, but not the intake
of the saccharin solution, reduced each monkey's food intake.
Because neither rats' sucrose nor monkeys' saccharin intakes
affected the slope of the respective demand curves for food,
monkeys and rats increased their daily output of presses and
thereby defended their daily intake of those complementary
elements of food. However, sucrose reduced rats' food intake. The
relative constancy of body weight and total caloric intake in the
sucrose condition is consistent with the possibility that rats
tended to regulate caloric intake.
Key words: closed economy, demand, substitution, regulation,
lever press, rats, monkeys