Simultaneous and successive choice in open and closed economies

摘要

Pigeons responded for food in simultaneous and successive choice procedures. In the simultaneous choice procedure, key pecks were reinforced according to concurrent-chains schedules of reinforcement. The average time from the onset of the initial links to a terminal link entry was held constant across conditions while the value of variable-interval schedules in the terminal links was varied. In the successive choice procedure, key pecks were reinforced according to multiple variable-interval variable-interval schedules of reinforcement. Equal duration components were increased in duration while the component rates of reinforcement were held constant, the component schedules were reversed, and component duration was decreased. For all subjects in the simultaneous choice conditions, and all subjects in the successive choice conditions, performance was assessed under two economic conditions: (1) an open economy in which session duration was limited to one-hour and subjects were maintained at 80% of their free-feeding body weight with post-session food when necessary; and (2) a closed economy in which sessions were 23.5 hours long and no deprivation regimen was in effect. The results from the simultaneous choice procedure showed that for all subjects, relative rate of responding in the initial links matched the reduction in overall delay to primary reinforcement correlated with entry into one terminal link relative to the reduction in delay correlated with entry into the other terminal link. While the sum of responses made in the initial links and terminal links was found to increase, then decrease, as the rate of food presentation decreased in the closed economy there was no consistent effect of overall rate of food presentation on total responding in the open economy. The choice data suggest that relative delay-reduction predicts choice accurately, regardless of economic context. For all subjects in the successive choice conditions, relative response rate decreased as components were lengthened in the open economy while in the closed economy relative rate increased as components were lengthened. Response proportions overmatched reinforcer proportions to a greater extent at long component durations in the closed economy, but there was no systematic effect of component duration on responding in the open economy.