Soto, P. L., McDowell, J. J, & Dallery, J. (2006).
Feedback functions, optimization, and the relation of response rate to
reinforcer rate.
Journal of the Experimental Analysis of Behavior, 85, 57-
71.
The present experiment arranged a series of inverted U-shaped feedback functions
relating reinforcer rate to response rate to test whether responding was
consistent with an optimization account or with a one-to-one relation of
response rate to reinforcer rate such as linear system theory’s rate equation or
Herrnstein’s hyperbola. Reinforcer rate was arranged according to a quadratic
equation with a maximum at a unique response rate. The experiment consisted of
two phases, during which 6 Long Evans rats lever pressed for food. In the first
phase of the experiment, the rats responded on six fixed-interval-plus-
quadratic-feedback schedules, and in the second phase the rats responded on
three variable-interval-plus-quadratic-feedback schedules. Responding in both
phases was inconsistent with a one-to-one relation of response rate to
reinforcer rate. Instead, different response rates were obtained at equivalent
reinforcer rates. Responding did vary directly with the vertex of the feedback
function in both phases, a finding consistent with optimization of reinforcer
rate. The present results suggest that the feedback function relating
reinforcer rate to response rate imposed by a reinforcement schedule can be an
important determinant of behavior. Furthermore, the present experiment
illustrates the benefit of arranging feedback functions to investigate
assumptions about the variables that control schedule performance.
Key words: optimization, feedback functions, linear system theory, Herrnstein’s
hyperbola, lever pressing, rats