Nevin, J. A., Grace, R. C., Holland, S., & McLean, A. P. (2001).
Variable-ratio versus variable- interval schedules: Response rate, resistance to change, and preference.
Journal of the Experimental Analysis of Behavior,
76, 43-74.
Two experiments asked whether resistance to change depended on
variable-ratio as opposed to variable-interval contingencies of
reinforcement and the different response rates they establish. In
Experiment 1, pigeons were trained on multiple random-ratio
random-interval schedules with equated reinforcer rates. Baseline
response rates were disrupted by intercomponent food, extinction,
and prefeeding. Resistance to change relative to baseline was
greater in the interval component, and the difference was
correlated with the extent to which baseline response rates were
higher in the ratio component. In Experiment 2, pigeons were
trained on multiple variable-ratio variable-interval schedules in
one half of each session and on concurrent chains in the other
half, in which the terminal links corresponded to the multiple-
schedule components. The schedules were varied over six
conditions, including two with equated reinforcer rates. In
concurrent chains, preference strongly overmatched the ratio of
obtained reinforcer rates. In multiple schedules, relative
resistance to response-independent food during intercomponent
intervals, extinction, and intercomponent food plus extinction
depended on the ratio of obtained reinforcer rates but was less
sensitive than was preference. When reinforcer rates were
similar, both preference and relative resistance were greater for
the variable-interval schedule, and the differences were
correlated with the extent to which baseline response rates were
higher on the variable-ratio schedule, confirming the results of
Experiment 1. These results demonstrate that resistance to change
and preference depend in part on response rate as well as
obtained reinforcer rate, and challenge the independence of
resistance to change and preference with respect to response rate
proposed by behavioral momentum theory.
Key words: variable-ratio schedules,
variable-interval schedules, resistance to change, response rate,
preference, key peck, pigeons