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Responses were maintained by a variable‐interval schedule of food reinforcement. At the same time, punishment was delivered following every nth response (fixed‐ratio punishment). The introduction of fixed‐ratio punishment produced an initial phase during which the emission of responses was positively accelerated between punishments. Eventually, the degree of positive acceleration was reduced and a uniform but reduced rate of responding emerged. Large changes in the over‐all level of responding were produced by the intensity of punishment, the value of the punishment ratio, and the level of food deprivation. The uniformity of response rate between punishments was invariant in spite of these changes in over‐all rate and contrary to some plausible a priori theoretical considerations. Fixed‐ratio punishment also produced phenomena previously observed under continuous punishment: warm‐up effect and a compensatory increase. This type of intermittent punishment produced less rapid and less complete suppression than did continuous punishment.

Male, medical and graduate students were subjected to a non‐discriminated avoidance regimen with shock‐shock and response‐shock intervals of 10 sec. Using a yoked‐chair procedure it was found that acquisition of the button‐pressing avoidance response was influenced by the social environment in which the conditioning occurred. There was a significantly greater number of “learners” among subjects conditioned individually than among those exposed to the conditioning procedures in the presence of a second person.

Two pigeons were trained on a multiple VI‐1; VI‐4 min schedule for food reinforcement until a stable differential rate of response was established. Each component of the multiple schedule was in effect for 10 min and was separated from the other by 1 min time out. An Estes‐Skinner conditioned suppression procedure was superimposed on each component of the schedule. The relative magnitude of the suppression behavior was measured during its acquisition and extinction, and at CS durations of 100, 200, and 300 sec. The initial magnitude of the suppression behavior was less severe on the VI‐1 baseline than on the VI‐4, and it extinguished more rapidly on the VI‐1. As the relative duration of the CS was increased, the suppression behavior became less severe on both baselines, but the initial differential magnitude in the suppression remained intact.

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Some data on Sidman avoidance in the pigeon are presented to illustrate a technique of instrumental training which places minimal restriction upon the form of the reinforced response. The effect of a warning signal is demonstrated, and the course of discrimination‐reversal is described.

Rats were trained on a two‐valued auditory‐intensity discrimination for 5, 2, 1 or 0 days. Then, the bar‐press response rate was sampled in the presence of seven added discrimination stimuli (generalization) for seven days. Daily training sessions were 4 hr in length throughout the experiment. Only the five‐day group exhibited a marked superiority on the multi‐valued discrimination when contrasted with the group having had no prior simple discrimination training.

Severely retarded, blind children were conditioned to respond differentially to two intensities of a pure tone. Gradients of auditory generalization were obtained that were reliable and similar to those for normal adults, but often asymmetric and nonmonotonic.

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Much of the available literature on avoidance behavior is based on responses which require the animal to run, lever‐press, or to make some active response to avoid noxious stimulation. The purpose of Experiment I reported in this paper was to determine whether animals can learn to sit or stand motionless in order to escape or avoid electric shock. Five experimental rats were given escape‐avoidance training, while five yoked control animals received electric shocks without any response‐related contingency. It was shown that an immobility avoidance response, as distinct from the unconditioned “freezing” response to shock, can be trained. The results of Experiment II (30 rats) revealed that this response is more readily acquired at higher shock intensities than at lower ones, provided escape by jumping is prevented at the high shock intensities. The effects of six doses of each of three drugs on the immobility avoidance response were studied in Experiment III (13 rats). Methylphenidate, chlorpromazine, and imipramine all produced a decrement in the immobility response, but the pattern and amount of the effects of the three drugs were quite different, one from the other. The implications of these findings for a general theory of avoidance behavior and for drug screening are discussed.

Daily food intake in rats was temporarily reduced by the introduction of an activity wheel and temporarily increased by the subsequent removal of the wheel. When this outcome is coupled with the positive relation between food deprivation and running—and food deprivation is seen as a loss of eating rather than as a physiological state—there is the suggestion that the total behavior output of the organism may be regulated as such. Specifically, when the rat is deprived of a behavior that recurrently comprises a large part of its total daily actiyity, an increase may occur in some other behavior.