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Three retarded and four economically disadvantaged children were taught, through modelling and reinforcement procedures, to produce complete sentences in response to three types of questions involving changes in verb inflections. To evaluate generalization of training, new but similar questions were periodically asked, answers to which were never modelled or reinforced. Modelling and reinforcement effectively taught correct sentence answers to training questions and produced new sentence answers to questions for which no specific training had been given.

The efficacy of several methods of aversive control of excessive alcoholic drinking was investigated in a semi‐naturalistic setting that permitted objective measurement of the drinking behavior of chronic alcoholics. Studies 1A and 1B compared an escape‐conditioning procedure with a control procedure in which aversive electrical shocks were administered before drinking. Neither procedure effectively decreased subjects' pretreatment, baseline alcoholic drinking behavior. In Study 2, aversive response‐contingent shocks effectively suppressed alcoholic drinking, but drinking subsequently returned to its former levels after withdrawal of punishment. Self‐administered shock appeared to be as effective as experimenter‐administered punishment for controlling drinking, even when the punishment contingency was faded out over time. Study 3 replicated the suppressant effect of punishment, and demonstrated that contingent shock was significantly more effective than yoked, noncontingent shock. A direct comparison of self‐ versus experimenter‐administered punishment suggested a possible slight advantage for the latter.

Two experiments were conducted to extend the blocking effect to the reinforcement of a response. A delayed reinforcement contingency was presented to subjects with or without a previously pretrained response available during the delay interval. The interpolated response had no scheduled effect on delivery of the reinforcer, but its availability reduced strengthening of the initial response, which completely extinguished for some subjects. The results were interpreted as support for blocking as a fundamental principle of behavior, and as evidence against the principle of reinforcement being stated solely in terms of temporal proximity between response and reinforcer.

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During the extinction component of a multiple variable‐interval extinction schedule, four pigeons learned to peck a second key that switched off the keylights. Two experiments attempted to isolate the events that control this behavior. In the first experiment, switching into blackout was equally maintained when switches were restricted to the first minute as when they were restricted to the last minute of the extinction component. When switches could be emitted in the first and last minutes, they occurred more frequently in the first. Restricting switching to the first minute of each component and eliminating the blackout between components had no effect on switching. In the second experiment, when the stimulus correlated with extinction was omitted, switching decreased slightly. Omission of both multiple schedule stimuli decreased the switching rate, but switching was still maintained. Food reinforcement was then omitted and switching by two birds increased. Switching ceased when blackout was no longer the consequence of pecking the switching key. It was concluded that switching was not controlled by the similarity of the blackouts produced by the switching key and those that occurred between components; nor was it maintained by the temporal proximity of switching responses to the onset of the reinforced component. Finally, switching did not appear to be controlled by the main‐key stimuli correlated with the components of the multiple schedule.

Four rats were trained in darkness on a free‐operant avoidance procedure in which shocks occurred randomly, but lever presses could reduce their frequency. Discrimination training followed, during which responses in light continued to reduce shock frequency, but responses in darkness had no effect. During each cycle, the light period was 4 min, while darkness lasted only until a 20‐sec interval had elapsed without a response. This no‐response requirement was increased to 40 sec for three animals and eventually to 60 sec for two of them. Discriminative control developed, despite a greater shock density in the dark, with response rate and number of responses per shock maintained or increasing during light and decreasing to very low values in darkness. Two animals were later exposed to a procedure in which shock density was unaffected by responding either in light or darkness. A 60‐sec no‐response requirement was continued in the dark. Discriminative control persisted through 42 sessions for one animal and required 45 sessions to approach extinction for the other animal. The role of the light as a potential conditioned reinforcer of other behavior in the dark was implicated in the development and persistence of discriminative control. These data support shock‐frequency reduction as reinforcement for avoidance behavior.

The effect of the size of the floor area of the operant test chamber on behavior was tested using a standard‐size test chamber and a test chamber with one‐fourth of the floor area of the standard chamber. Two groups of pigeons were tested under a differential‐reinforcement‐of‐low‐rate 15‐sec schedule or a variable‐interval 60‐sec schedule. Both groups of pigeons had higher response rates while in the smaller floor area. Pigeons under the differential‐reinforcement‐of‐low‐rate schedule also showed a decrease in rate of reinforcement, an increase in ratio of responses to reinforcements, and an alteration in interresponse‐time‐per‐opportunity distributions when tested in the reduced floor‐area condition. These effects are similar to those found under physical restraint, indicating that amount of floor space available for locomotion interacts with schedule behavior and that physical restraint may be regarded as the lower limiting value of amount of floor area available for locomotion.

Responding was maintained in squirrel monkeys under variable‐interval schedules of electric shock presentation when a period of timeout followed each response‐dependent shock. Response rate decreased when timeout duration was decreased, and responding ceased when timeout was eliminated. These results indicate that under certain conditions, a shock‐free period following each response‐produced shock is necessary to maintain responding.