The delivery of food contingent on 10 s of consecutive toy engagement resulted in a decrease in engagement and a corresponding increase in other responses that had been previously reinforced with food. Similar effects were not observed when tokens exchangeable for the same food were delivered, suggesting that engagement was disrupted by the…

Responding of 4 children was assessed under conditions in which (a) no programmed contingencies were arranged for target behavior, (b) responding produced tokens that could be exchanged for a single highly preferred edible item, and (c) responding produced a token that could be exchanged for a variety of preferred edible items. After assessing the…