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Squirrel monkeys were trained on a multiple schedule in which 10‐min periods on a continuous shock avoidance schedule, indicated by a yellow light, alternated with 10‐min periods on a 1.5‐min variable interval schedule of food reinforcement (VI 1.5). A white light indicated that VI 1.5 was in effect, except for the middle 2 min of the period on VI 1.5, in which a blue light appeared and terminated with the delivery of a 0.5‐sec unavoidable shock. Stable response rates developed in the avoidance and VI 1.5 components. However, the highest response rates occurred in the blue, preshock stimulus. A series of experiments showed that responding in the blue stimulus persisted even when responding had been extinguished on both the VI schedule of food reinforcement and the shock avoidance schedule. Responding in the blue stimulus ceased when the blue stimulus terminated without shock or when it terminated with a response‐contingent shock. Each time responding ceased, it was restored by terminating the blue stimulus with an unavoidable shock. When the blue stimulus was on throughout each session and unavoidable shocks were delivered at regular 10‐min intervals, responding was well maintained. These results show that in monkeys that have been trained on a continuous avoidance schedule, unavoidable shocks can maintain responding even under conditions where responses have no programmed consequences.

In a temporally defined system of reinforcement schedules, the fixed interval case is defined when reinforcement probability, P, is equal to unity for the first response in any cycle length, T; when P is less than 1.0, random interval schedules emerge wherein T/P specifies the expected interval between reinforcements. Key‐pecking rates were found to be: (a) inversely related to T/P; (b) higher at T = 1.0 second than at other T parameter values; (c) low and linear at several T and T/P values. The mean post‐reinforcement pause, if initially small, increased, and if initially large, decreased, as T/P increased.

A system of punched card programming and recording of primate discrimination learning experiments is described to illustrate the application of these techniques to the automation of the discrete trial learning situation, allowing for punched card recording and subsequent digital computer data analyses without intermediate data reduction. The system was also designed to control several potential sources of variability inherent in the conventional WGTA testing mode, including 1) the subject's (S's) motivation to test on each trial, 2) S's attention to the stimuli, and 3) the rate of trial presentation so as to be more under S's control. Reliable techniques of punched card programming and recording are detailed.

Human subjects were intermittently reinforced with money for performing correctly on a conditional matching‐to‐sample task. The matching performance was examined as a function of a) the duration of Time‐Outs (TOs) which followed every incorrect response and b) the frequency (FR value) with which TOs followed incorrect responses. The matching accuracy increased with longer TOs and decreased with less frequent presentation of TOs.

The responses of pigeons were maintained by a DRL schedule of food reinforcement. With this schedule, responses were reinforced only when a fixed period of time elapsed without an intervening response. Punishment of all responses reduced the frequency of these responses as a direct function of the punishment intensity. As a consequence of the increased temporal spacing of responses, more reinforcements resulted during punishment. Under progressively higher intensities of punishment, the reinforcement frequency increased to a maximum value and then decreased at the highest intensities. The increased frequency of reinforcement which resulted during punishment did not counteract the suppressive effect of punishment, nor did it lead to a low response rate after punishment was removed. Punishment did not reduce the inter‐response time distribution uniformly, but rather especially reduced the number of short inter‐response times. Even at the low punishment intensities, the number of short inter‐response times was considerably reduced. After punishment was discontinued, performance recovered almost completely after a compensatory burst. The number as well as the temporal pattern of responses returned to normal.

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