Hedonic scaling of sugars using concurrent operant schedules with dogs

An experiment is reported with 5 beagles in which the concurrent operants procedure was used to scale glucose and fructose against a "standard" sugar, sucrose. The sugars were in solution and the dogs were required to lever-press to obtain access to the solutions. In the first part of the experiment, the dogs chose between fructose and sucrose, and between glucose and sucrose, in a series of tests where different volumes of the two sugars were available for pressing the two levers. This arrangement made it possible to construct an empirical function for each pair of sugars showing the relation between relative strength of responding on the levers and the relative volumes of fluids obtained. From these functions it was possible to predict the ratio of fluid-volumes that would render hedonic equivalence. The data supported the prediction, indicating the ability of the concurrent schedules procedure to scale qualitatively different food-items in dogs.