Schedule-induced wheel-running: effects of exposure to the schedule

Rats were given access to a running wheel from a chamber where milk was delivered according to a fixed-time 1-min schedule. For most animals the effect of the schedule was to decrease wheel-running rate below that during massed reinforcement control sessions. With further exposure to the schedule wheel-running rate tended to increase and a well-defined temporal pattern developed. Subsequent exposure to the control condition caused an initial increase and then, in most cases, a decline in wheel-running rate. Re-exposure to the schedule increased wheel-running rates in three out of four subjects and the temporal pattern developed more rapidly. Judgement as to whether a particular behavior pattern is schedule-induced or not can only be reliably made when there is strong evidence that the overall rate and temporal pattern of the behavior are stable. Wheel-running appears to be a schedule-induced behavior under some experimental conditions.