Behavioral effects of changeover delays in a concurrent-chains schedule with different delays and magnitudes of reinforcement

The present study examined the effects of a changeover delay (COD) on the choice between smaller, shorter delayed reinforcement and larger, longer delayed reinforcement in a complex concurrent-chains schedule. Four pigeons were exposed to three conditions in an ABA or BAB reversal design. A COD of 2 seconds was included in the initial links during condition B. The concurrent-chains schedule had identical variable-interval schedules in the initial links and different delays and magnitudes of reinforcement that were programmed according to a fixed-ratio 10 (FR10) schedule in the terminal links. Each experimental condition lasted for two long sessions and five short sessions. Changeover rates were lower, and preference for the larger, longer delayed reinforcer was more pronounced during conditions with the programmed 2-second COD. The analysis of initial pauses and running rates during the FR10 schedules of the terminal links revealed no systematic effects of the COD on behavior in the terminal links. The COD had similar effects on choice performance in this modified concurrent-chain procedure as on simple concurrent performance.Keywords: Choice behavior, concurrent-chains, COD, self-control paradigm, pigeons.