EFFECTS OF ETHANOL ON BEHAVIOR UNDER FIXED-RATIO, FIXED-INTERVAL, AND MULTIPLE FIXED-RATIO FIXED-INTERVAL SCHEDULES IN PIGEON

Abstract

Behavior of pigeons was controlled by fixed-ratio [FR], fixed-interval [FI] and multiple fixed-ratio fixed-interval [FR-FI] schedules of reinforcement. When each 30th 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 FI schedule the 1st 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 FI schedule. When the FR and FI schedules alternated regularly throughout a single experimental session (multiple FI-FR schedule), differential effects that depended upon the schedule of reinforcement were still obtained. Ethanol affected local rates of responding within the FI differently depending upon the rates prior to drug administration; low rates were increased while higher rates were decreased. The effects of ethanol on schedule-controlled responding depended upon the particular rates and patterns of responding maintained by the schedule of reinforcement.