Behavioral momentum and accumulation of mass in multiple schedules

Behavioral momentum theory suggests that the relation between a discriminative-stimulus situation and reinforcers obtained in that context (i.e., the Pavlovian stimulus-reinforcer relation) governs persistence of operant behavior. Within the theory, a mass-like aspect of behavior has been shown to be a power function of predisruption reinforcement rates. Previous investigations of resistance to change in multiple schedules, however, have been restricted to examining response persistence following protracted periods of stability in reinforcer rates within a discriminative situation. Thus, it is unclear how long a stimulus-reinforcer relation must be in effect prior to disruption in order to affect resistance to change. The present experiment examined resistance to change of pigeon's key pecking following baseline conditions where reinforcer rates that were correlated with discriminative-stimulus situations changed. Across conditions, one multiple-schedule component arranged either relatively higher rates or lower rates of variable-interval food delivery, while the other component arranged the opposite rate. These schedules alternated between multiple-schedule components across blocks of sessions such that reinforcer rates in the components were held constant for 20, 5, 3, 2, or 1 session(s) between alternations. Resistance to extinction was higher in the component that most recently was associated with higher rates of food delivery in all conditions except when schedules alternated daily or every other day. These data suggest that resistance to change in multiple schedules is related to recently experienced reinforcer rates but only when multiple-schedule components are associated with specific reinforcer rates for several sessions.