The drinking of saccharin solutions by nondeprived rats was found to increase on initial exposure as a function of daily sessions and not as a function of previous state of deprivation or vigor of drinking. Large and persisting positive and negative successive contrast effects followed a single shift in concentration. Forcing the drinking to occur in short bouts by withdrawing the drinking tube elevated total intake above the level established by the positive and negative contrasts. The drinking returned to baseline when uninterrupted drinking was permitted. Maximum drinking occurred with 10- and 20-min interruptions of 2-min drinking periods. Consecutive daily interrupted drinking sessions did not produce further increases in drinking, as might have been predicted by opponent process theory or by a classical conditioning interpretation. It was suggested that the persistence of the positive and negative contrasts was dependent on the limited past experience of the animals with the saccharin taste, and that the enhancement of drinking by interruption may depend on the increased excitement produced by drinking tube withdrawal and the reduction of the excitement by reintroduction of the tube. © 1988 Psychonomic Society, Inc.