to indicate availability of the reinforcer in the dipper receptacle. The dipper port was illuminated for 10 seconds whilst the dipper cup was available. If the cup was not actively licked during the 10 seconds, the cup fell and this event was recorded as a null response. Lever pressing during the 10 seconds were also recorded but did not result in any programmed activity. During the overnight sessions, only the active lever was available for the rat to press, to facilitate learning. Following the completion of these sessions, rats were then exposed to 45-minute FR1 sessions for 1 week (5 sessions). Subsequently, training sessions were reduced to 30 minutes and the work ratio was increased to FR3 schedule of reinforcement (three active lever presses required for a 0.1 ml reward). The second (inactive) lever was also introduced at this time. Upon pressing the inactive lever, no reinforcer, cue light, or auditory stimuli were presented and the event was merely recorded as a measure of nonspecific behavior. Rats continued on the FR3 protocol with 20% ethanol as the reinforcer for a minimum of 24 sessions. Any animals that failed to receive any reinforcers (<1) during the last 5 operant sessions were
