Grace, R. C., & Nevin, J. A. (2000).
Comparing preference and resistance to change in constant- and variable-duration schedule components.
Journal of the Experimental Analysis of Behavior,
74, 165-188.
Two experiments explored preference and resistance to change in
concurrent chains in which the terminal links were
variable-interval schedules that ended either after a single
reinforcer had been delivered (variable duration) or after a
fixed period of access to the schedule (constant duration). In
Experiment 1, pigeons' preference between the same pair of
terminal links overmatched relative reinforcement rate when the
terminal links were of constant duration, but not when they were
of variable duration. Responding during the richer terminal link
decreased less, relative to baseline, when response-independent
food was presented during the initial links according to a
variable-time schedule. In Experiment 2, all subjects
consistently preferred a terminal link that consisted of 20-s
access to a variable-interval 20-s schedule over a terminal link
that ended after one reinforcer had been delivered by the same
schedule. Results of resistance-to-change tests corresponded to
preference, as responding during the constant-duration terminal
link decreased less, relative to baseline, when disrupted by both
response-independent food during the initial links and
prefeeding. Overall, these data extend the general covariation of
preference and resistance to change seen in previous studies.
However, they suggest that reinforcement numerosity, including
variability in the number of reinforcers per terminal-link entry,
may sometimes affect preference and resistance to change in ways
that are difficult to explain in terms of current models.
Key words: choice, concurrent chains, resistance to change,
behavioral momentum, reinforcement delay, key peck, pigeons