Temporal control of eating on periodic water schedules

Three pairs of rats were given periodic access to water at intervals of 40, 90, or 120 sec while food was continuously available. Excessive eating was not induced at any rate of water delivery, but the temporal pattern of eating was controlled by the water delivery schedules. At higher delivery rates, most eating occurred soon after water presentation: lower delivery rates resulted in progressively flatter temporal distributions. Temporal distributions of eating on periodic water schedules were consistent with Killeen's model of temporal control. Killeen's model also describes the similar temporal distributions of behaviors which occur at excessive rates induced by periodic food schedules. This suggests that common principles of temporal control govern interim behaviors entrained by periodic schedules regardless of either the nature of the scheduled event, e.g., food or water, or the effect of the schedule on the overall rate of responding.