Fig. 1.
Left-hand diagrams: Illustration of the adjusting-delay and adjusting-magnitude schedules. Adjusting-delay schedule. In free-choice trials, a response on lever A resulted in the delivery of a reinforcer after a short or a long delay, with equal probability; a response on lever B resulted in the delivery of a reinforcer after a delay dB, the length of which was adjusted in accordance with the subject's choices (see text for details). Adjusting-magnitude schedule. A response on lever A resulted in the immediate delivery of a small or a large reinforcer, with equal probability; a response on lever B resulted in the immediate delivery of a reinforcer whose size qB was adjusted in accordance with the subject's choices (see text for details). Right-hand graphs: representative performances of individual rats trained under each schedule; ordinate adjusting delay (dB, s) or magnitude (qB, μl) in successive blocks of trials during 60 training sessions (7 blocks per sessio). Horizontal lines show the two standard delays or magnitudes prescribed for reinforcer A.