Effects of ethanol on behavior under fixed-ratio, fixed-interval, and multiple fixed-ratio fixed-interval schedules in the pigeon.

Behavior of pigeons was controlled by fixed-ratio, fixed-interval and multiple fixed-ratio fixed-interval schedules of reinforcement. When each thirtieth peck on a response key produced food (fixed-ratio schedule) high rates of responding were maintained; low to intermediate doses of ethanol left unchanged or increased those rates. Under the fixed-interval schedule the first response after 5 min produced food and comparatively lower rates of responding were maintained that gradually increased up to food presentation. Low to intermediate doses of ethanol only decreased overall rates of responding under the fixed-interval schedule. When the fixed-ratio and fixed-interval schedules alternated regularly throughout a single experimental session (multiple fixed-ratio fixed-interval schedule), differential effects that depended upon the schedule of reinforcement were still obtained. Ethanol affected local rates of responding within the fixed intervals differently depending upon the rates prior to drug administration; low rates were increased while higher rates were decreased. As with other drugs, the effects of ethanol on schedule-controlled responding depended upon the particular rates and patterns of responding maintained by the schedule of reinforcement.