EFFECTS OF d ‐AMPHETAMINE AND CAFFEINE ON SCHEDULE‐CONTROLLED AND SCHEDULE‐INDUCED RESPONDING

Abstract

The effects of d ‐amphetamine and caffeine were studied on rates and patterns of lever pressing and schedule‐induced licking under fixed‐interval schedules of food pellet presentation. In addition, the effects of caffeine were studied on lever pressing and licking under a multiple fixed‐ratio fixed‐interval schedule. Caffeine reduced mean overall rates of licking at lower doses than it reduced mean overall rates of pressing under the fixed‐interval schedules, but the effects of caffeine on both licking and lever pressing depended largely on the control rate of responding. d ‐Amphetamine reduced mean overall rates of lever pressing and licking at about the same dose, but the effects of d ‐amphetamine also were a function of the control rate of responding.