Preference for food and water in rats as a function of delay of reward

Abstract

In Experiment I, rats which were both hungry and thirsty were given a choice between a food reward and a water reward. The animals preferred food to water when the reward was delivered immediately, but preferred water to food when a 30-sec delay was imposed in the goalbox before the reward was received. Experiment II replicated the results of the first experiment and showed, in addition, that when the delay was imposed in a separate delay chamber devoid of differential goalbox cues, subjects preferred food to water, similar to the immediate group. The results were discussed in terms of an incentive value process and a competing response hypothesis.