Determinants of reinforcer accumulation during an operant task

Responses by rats on an earn lever made available food pellets that were de livered to a food cup by responses on a second, collect, lever. The rats co uld either collect and immediately consume or accumulate (defined as the pe rcentage of multiple earn responses and as the number of pellets earned bef ore a collect response) earned pellets. In Experiment 1, accumulation varie d as a function of variations in the earn or collect response requirements and whether the earn and collect levers were proximal (31 cm) or distal (24 8 cm) to one another. Some accumulation occurred under all but one of the c onditions, but generally was higher when the earn and collect levers were d istal to one another, particularly when the earn response requirement was f ixed-ratio (FR) 1. In Experiment 2, the contributions of responses and time to accumulation were assessed by comparing an FR 20 earn response requirem ent to a condition in which only a single earn response was required at the end of a time interval nominally yoked to the FR interval. When 248 cin se parated the earn and collect levers, accumulation was always greater in the FR condition, and it was not systematically related to reinforcement rate. In Experiment 3, increasing the earn response requirement with a progressi ve-ratio schedule that reset only with a collect response increased the lik elihood of accumulation when the collect and earn levers were 248 cin apart , even though such accumulation increased the next earn response requiremen t. Reinforcer accumulation is an understudied dimension of operant behavior that relates to the analysis of such phenomena as hoarding and self-contro l, in that they too involve accumulating versus immediately collecting or c onsuming reinforcers.