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White rats were scheduled to be shocked every 15 sec; but they were given a limited time interval between shocks when they could prevent the next scheduled shock from occurring if they pressed a lever. The duration of this limited avoidance period was varied, as was its location within the interval between scheduled shocks. Response rate, shock frequency, and the temporal distribution of lever presses were examined. Conditions were generated in which the formation of a temporal discrimination prevented the animals from maintaining successful avoidance behavior.

A series of experiments is reported in which two monkeys emitted complex response patterns, not specified by the experimental program, during the DRL component of a multiple schedule. Administration of sodium pentobarbital and dl‐amphetamine, drugs which disrupted the DRL performance, were also observed to suppress these collateral responses. Sequences of these collateral responses appear to mediate, at least in part, the timing process required for reinforced performance on the DRL schedule.

In the presence of a bright light, monkeys were trained to press a lever to avoid shock and to pull a chain for food reward. After gradients of generalization to other light intensities had been determined for each response, gradients were subsequently secured after training in a brightness discrimination and under several free‐shock conditions. The following results were obtained: (1) Generalization gradients prior to discrimination training were much steeper for the food‐controlled response than for the shock‐controlled response. This finding was confirmed in another study in which rats served as subjects. (2) After discrimination training, both gradients became much steeper, but the avoidance gradient still showed more generalized responding than that of reward. (3) After a period of continuous testing with all the different test intensities, the two gradients became even steeper. In addition, differences between the two gradients virtually disappeared. (4) The intermittent delivery of free shocks during a previously non‐shocked light intensity radically affected the shape of the avoidance gradient, just as the addition of an avoidance contingency did during the same, previously non‐shocked, light intensity.

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Operant‐conditioning principles using food as a reinforcer were applied to control the behavior of 45 chronic schizophrenic patients. The investigation was conducted in a psychiatric ward in which there was 24‐hr environmental control.In order to use food as a reinforcer for controlling psychotic behavior, it was necessary first to deal with the eating deficits in the patients. Approximately 50% of the ward population was selected because of a history of refusal to eat. Their refusal to eat had remained relatively unaffected by one or more of these treatments: spoonfeeding, tubefeeding, intravaneous feeding, and electroshock. These treatments were discontinued, and the patients were left alone at mealtimes. The results show that social reinforcement in such forms as coaxing, persuading, and feeding the patient tend to shape patients into eating problems so they are conditioned to eat only with assistance. When refusal to eat was no longer followed by social reinforcement, the patients soon started eating unassisted. When access to the dining room was made dependent upon a chain of responses including a motor and social component, all patients learned these responses.

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