Value of conditioned reinforcers as a function of temporal context

In two experiments, pigeons were trained on a multiple-chain schedule, in which the initial link for one chain was a variable-interval (VI) 100 s schedule and for the other chain a VI 10 s schedule. The terminal links were both fixed-time 30 s schedules signaled by differently colored stimuli. Following training, the pigeons had their preference for the terminal-link stimuli tested either by presenting these stimuli in concurrent probes or by presenting these stimuli as reinforcement for completing novel initial links. In Experiment 1, pigeons significantly preferred the terminal-link stimulus that followed the long initial link in three of the five conditions. This preference was observed across all three testing procedures (concurrent chains, concurrent chains probes, and concurrent probes). Experiment 2 was a replication of this effect in one of the conditions from Experiment 1. The results demonstrate that temporal context does impact the value of a conditioned reinforcer in a manner consistent with delay-reduction theory, and inconsistent with other choice theories, such as the contextual choice model and scalar expectancy theory.