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Rats were reinforced with water for every bar-press and concurrently punished for every 10th or 20th bar-press. Punishment produced an initial suppression of responding followed by recovery. A slight change in the method of delivering punishment eventually led to a high response rate just after punishment, a low response rate just before punishment, and frequent intermediate pauses. The results are interpreted as showing that punishment became a safe signal and that the high rate of responding it released came to act as a conditioned aversive stimulus. The effects of amphetamine were consistent with this interpretation. Alcohol had the paradoxical effect of increasing pauses and depressing the low rate before punishment. Azrin (1956) Consequently, the reinforcement schedule would counteract any tendency of the punishment schedule to produce high rates. This consideration is less relevant to Azrin's original study of response-correlated shock, in 'Reprints may be obtained from

Four rats were trained to bar press on FR 9 TO 30 sec. They were reinforced with a large or small amount of water according to whether their final IRT was long or short respectively. Four control rats always received the small amount of reinforcement. The control animals produced the high rates of responding typical of fixed-ratio performance. The experimental animals, with one exception, developed superstitious behavior and maintained slow responding throughout the ratio. However, some features of the results pointed to a persistent influence of the factors which favor short IRTs.Response rate on a fixed-interval schedule can be controlled within wide limits by making amount of reward depend on the length of the final IRT (Hendry, 1962 The Ss were initially given magazine training and CRF, followed by FR 5. After the delivery of each reinforcement, the white signal lamp above the lamp went off for 30 sec. During this time responses were neither reinforced nor counted towards the next ratio requirement. The schedule is abbreviated as FR 5 TO 30". After two sessions of FR 5 TO 30" the schedule was FR 9 TO 30" for a further 70 sessions.The water reinforcement was either a large amount or a small amount. The actual volumes varied during the experiment. The Cs always received the small amount on the final bar-press. The Xs received the small amount if their final IRT was shorter than a criterion, and the large amount if it was longer. Because higher rates produce smaller amounts of reinforcement, this procedure has been called negatively correlated amount of reward. The actual relation between the final IRT and the reward is called the "terms" (Logan, 1960). The terms were chosen on the basis of performance in the previous session so that about half of the rewards would be large. For the first 23 sessions, and during the preliminary training on FR 5 TO 30", the amounts of reward were 0.05 ml and 0.25 ml. During sessions 24-50 the amounts were 0.02 ml and 0.10 ml, and thereafter 0.02 ml and 0.16 ml.After session 59, a piece of brass angle was attached to the wall below the bar, for the Xs 207 VOLUME 7, NUMBER 2 MARCH, 1 964

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