AbstractThis study examined choice of beer over an alternative, non‐drug reinforcer (food or money), under conditions where the magnitude and availability of the non‐drug reinforcer was varied. Normal volunteers participated in three sessions consisting of a computerized choice task followed by a period of relaxation and consumption of earned reinforcers. The computer task consisted of a concurrent choice schedule in which the availability of the non‐drug reinforcer was varied across ‘trials’ from random ratio 1.3 to 16 (probability of reinforcement: 75 per cent to 6 per cent). Across the three sessions the magnitude of the non‐drug reinforcer was varied (i.e. small, medium, large). The magnitude and availability of beer remained constant across trials at a random ratio 4 (probability of reinforcement: 25 per cent). Two experiments were conducted, one in which food was the alternative reinforcer (Experiment I) and one in which money was the alternative reinforcer (Experiment II). In both experiments, decreasing the response requirement for the non‐drug reinforcer within the sessions resulted in an orderly decrease in the amount of responding to obtain alcohol. In Experiment I, changes in the magnitude of the food reinforcer did not change responding for beer. In Experiment II, however, responding for beer decreased when the magnitude of the alternative monetary reinforcer was increased. Thus, changes in the magnitude of an alternative reinforcer may have differential effects on responding for a drug reinforcer, depending on the nature of the alternati
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