Pavlovian contingencies and resistance to change in a multiple schedule

According to theoretical accounts of behavioral momentum, the Pavlovian sti mulus-reinforcer contingency determines resistance to change. To assess thi s prediction, 8 pigeons were exposed to an unsignaled delay-of-reinforcemen t schedule (a. tandem variable-interval fixed-time schedule), a signaled de lay-of-reinforcement schedule (a chain variable-interval fixed-rime schedul e), and an immediate, zero-delay schedule of reinforcement in a three-compo nent multiple schedule. The unsignaled delay and signaled delay schedules e mployed equal fixed-time delays, with the only difference being a stimulus change in the signaled delay schedule. Overall rates of reinforcement were equated for the three schedules. The Pavlovian contingency was identical fo r the unsignaled and immediate schedules, and response-reinforcer contiguit y was degraded for the unsignaled schedule. Results from two disruption pro cedures (prefeeding subjects prior to experimental sessions and adding a va riable-time schedule to timeout periods separating baseline components) dem onstrated thai response-reinforcer contiguity does play a role in determini ng resistance to change. The results from the extinction manipulation were not as clear. Responding in the unsignaled delay component was consistently less resistant to change than was responding in both the immediate and pre signaled segments of the signaled delay components, contrary to the view th at Pavlovian contingencies determine resistance to change. Probe tests furt her supported the resistance-to-change results, indicating consistency betw een resistance to change and preference, both of which are putative measure s of response strength.