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A pigeon's responses were reinforced on a variable‐interval schedule on one key; and, concurrently, either a multiple or a fixed‐interval schedule of reinforcement was in effect on a second key. These concurrent schedules, conc VI 3 (mult VI 3 EXT) or conc VI 3 FI 6, were programmed with or without a changeover delay (COD). Because the COD provided that responses on one key could not be followed by reinforced responses on the other key, responding on one key was not likely to accidentally come under the control of the reinforcement schedule on the other. When the COD was used, the performances on each key were comparable to the performances maintained when these interval schedules are programmed separately. The VI schedule maintained a relatively constant rate of responding, even though the rate of responding on the second key varied in a manner appropriate to the schedule on the second key. The mult VI 3 EXT schedule maintained two separate rates of responding: a relatively high rate during the VI 3 component, and almost no responding during the EXT component. The FI schedule maintained the gradually increasing rate of responding within each interval that is characteristic of the performance maintained by this schedule. The concurrent performances, however, did include certain interactions involving the local characteristics of responding and the over‐all rates of responding maintained by the various schedules. The relevance of the present findings to an inter‐response time analysis of VI responding, a chaining account of FI responding, and the concept of the reflex reserve was discussed.

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In Experiment I, three groups of 20 Ss each were exposed to a light of 550 mμ (yellowish‐green) for 60 sec and then viewed a random sequence of wavelengths with instructions to respond only to the original color. The instructions given the three groups were worded differently in an attempt to vary the strength of a set‐to‐discriminate assumed to be created by this procedure. The three groups produced similar gradients, each with a peak of responding at 540 mμ, in agreement with Kalish's (1958) published gradient for the 550 mμ standard stimulus value. It was suggested that the nature of the task is such that a strong discriminatory set is produced regardless of the wording of the instructions.A temporal analysis of the gradient as it develops during the testing revealed that initially the peak of responding occurs at 550 mμ; but as testing progresses, it shifts gradually in the direction of the shorter wavelengths (purer greens). Experiment II was performed to test the generality of the phenomenon of regression to the primary color. Two groups of 20 Ss each were tested for generalization following exposure to 510 mμ (bluish‐green) and 525 mμ (pure green), respectively. We predicted that the 510 mμ gradient would reveal a progressive shift toward the longer wavelengths (purer greens), whereas the 525 mμ gradient would show no tendency to shift. The results were strikingly in accord with these predictions.We concluded that although a physiological process could not be ruled out, the verbal labeling of the standard stimulus value may well be responsible for the regression of the gradient toward the primary color.

Punishment acquires a discriminative property when it is selectively paired with either reinforcement or extinction. At the milder punishment intensities, the discriminative control exerted by punishment is similar to the discriminative control exerted by a response‐produced neutral (nonaversive) stimulus. However, the effect of the aversive property is apparent as the intensity of the punishment is increased. The aversive property of the punishment acts to enhance the discriminative control when the punishment is selectively applied during extinction periods, and to attenuate the discriminative control when the punishment is selectively applied during reinforcement periods. One major difference was found between the control exerted by the punishment and the response‐produced neutral simulus: Responding greatly increased after the SΔ punishment but not after the SΔ neutral stimulus; this increase in responding was independent of the punishment intensities studied.

Four male pigmented rats were exposed to a procedure designed to investigate the relation between several performance measures and a schedule continuum ranging from FR 36 to FI 2 through four intermediate interlocking schedules. On all schedules, each subject developed a stable performance that was generally break‐and‐run. Analysis of the cumulative records, post‐SR breaks, and running rates showed a continuum of performance related to the schedule continuum.

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A 5‐year‐old boy was shown cartoons, and punished for thumbsucking during alternate cartoons by turning off the cartoons for as long as his thumb remained in his mouth. Thumbsucking weakened during such periods. During alternate periods of uninterrupted cartoons, thumbsucking promptly recovered, suggesting a quick discrimination process. Two other 5‐year‐old boys were shown the same cartoons; withdrawal of the cartoons was made contingent upon thumbsucking for one, and randomly yoked for the other. Then their roles were reversed. Contingent withdrawal and re‐presentation of the cartoons controlled thumbsucking rate; yoked withdrawal and re‐presentation did not.

A procedure is described by which a machine defines the ongoing silent and oral reading rates, and thus subjects them to environmental control and experimental analysis. Reading is considered as a form of monitoring in which response sequences are linear and successive. Applications for other types of monitoring are considered.A page is projected on a screen, and the subject is required to read, aloud or silently. Through the same optical system, an opaque loop is presented that masks the projection, and a transparent slit on the opaque loop exposes part of a line of type. With each frame, the slit moves linearly and sequentially, exposing successive reading material. Recycling the loop triggers the presentation of another page. The subject controls the loop by pressing a microswitch to advance the frame, thereby explicitly defining a monitoring response. The procedure is sensitive to variables such as signal‐noise ratio, item difficulty, transient and long‐term effects, reinforcement schedules (pay‐offs), and age. Monitoring rates are extremely steady, suggesting their use as a base line.Procedures are suggested for training subjects to be differentially attentive to different parts of a complex display.

Cats were trained to respond on a multiple discriminative schedule, with milk as reinforcement. Two subjects did not immediately consume the reinforcer when they were injected with 6 mg of methylphenidate before the experiment. This observation could be repeated in one of the subjects under various conditions of reinforcement and various doses of the drug. Control experiments showed that under normal conditions the same cats never ignored the reinforcer. The modification induced by the drug in the relationship between behavior and the reinforcement is discussed in its bearing on the notion of reinforcer.