Field, D. P., Tonneau, F., Ahearn, W., & Hineline, P. N. (1996).
Preference between variable-ratio and fixed-ratio schedules: Local and extended relations.
Journal of the Experimental Analysis of Behavior,
66, 283-295.
Although it has repeatedly been demonstrated that pigeons, as
well as other species, will often choose a variable schedule of
reinforcement over an equivalent (or even richer) fixed schedule,
the exact nature of that controlling relation has yet to be fully
assessed. In this study pigeons were given repeated choices
between concurrently available fixed-ratio and variable-ratio
schedules. The fixed-ratio requirement (30 responses) was
constant throughout the experiment, wheareas the distribution of
individual ratios making up the variable-ratio schedule changed
across phases: The smallest and largest of these components were
varied gradually, with the mean variable-ratio requirement
constant at 60 responses. The birds' choices of the
variable-ratio schedule tracked the size of the smallest
variable-ratio component. A minimum variable-ratio component at
or near 1 produced strong preference for the variable-ratio
schedule, whereas increases in the minimum variable-ratio
component resulted in reduced preference for the variable-ratio
schedule. The birds' behavior was qualitatively consistent with
Mazur's (1984) hyperbolic model of delayed reinforcement and
could be described as approximate maximizing with respect to
reinforcement value.
Key words: choice, concurrent schedules, delay of reinforcement,
schedule variability, ratio schedules, key peck, pigeons