Preference history prevents schedule-induced preferential ethanol acceptance.

Two groups of rats were given differential schedule-induced polydipsia histories. One had a history of choosing between 5% ethanol and 0.7% glucose solution (dilute, mildly acceptable), in daily, 3-hr, fixed-time 1-min schedules of food-pellet delivery, while the other similarly treated group chose between 5% ethanol and 5% glucose (highly acceptable). A 30-day period, wherein only 5% ethanol was available during daily sessions, intervened before session-fluid preferences were evaluated by pitting a series of glucose solutions of increasing concentration (0.7-5.0%) against 5% ethanol. The group which had a remote history of having chosen 5% glucose solution in preference to 5% ethanol imbibed less 5% ethanol during the series of glucose-ethanol acceptability preference tests. Hence, they were less vulnerable to a continuance of their ethanol overindulgence than the group with the remote history of having chosen 5% ethanol over the dilute glucose solution.