Choice in transition and changeover response requirements in concurrent dependent and independent schedules of reinforcement [Elecciíon en transición y requisitos de respuesta de cambio en programas concurrentes independientes y dependientes]

Abstract

Sensitivity to reinforcement increases with increasing changeover response requirements. This result has been documented with stationary choice in concurrent variable interval (VI-VI) independent schedules of reinforcement, as well as, in concurrent VI-VI schedules where the availability of reinforcers is dependently scheduled. The present study assessed the generality of this finding with choice in transition. Within sessions the ratio of reinforcers changed seven times in two levers, modeling a dynamic environment. Twelve rats responded to the levers for food reinforcers. To switch from the lean to the rich lever, a third changeover-lever increased the response requirement in nine steps of 8 responses each; only one response was required to switch from the rich to the lean lever. In Experiment 1 (forced choice) the reinforcers were dependently scheduled in the levers, but in Experiment 2 (free choice) the reinforcers were independently arranged by the schedules. Choice adjusted rapidly to the dynamic changes in the ratio of reinforcers. In Experiment 1 sensitivity to reinforcement increased, but in Experiment 2 it decreased with increasing changeover response requirement.