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Pigeons were studied in a delayed‐response task requiring alternation of key pecks on two response keys. Blackouts of from 1 to 10 sec intervened between successive choices on the two keys.The following results were obtained: (1) Birds performed at well above chance accuracy on all the delays tested. Accuracy was generally lowest at 1‐ and 10‐sec delays. (2) Overt postural orientations during the delay interval appeared to mediate accurate key‐pecking behavior. (3) The shape of the delay vs. accuracy function was discussed in terms of the possibly confounding influences of (a) stimulus “trace” variables, and (b) aversive effects of the time outs produced by incorrect responding.

Four rats had continuous access to activity wheels first, then access for 1 hr per day, and, subsequently, continuous access. Limiting S's access to the wheel substantially increased the total frequency of running. A distributional analysis of response duration, burst duration, and interburst interval showed that the increased frequency arose almost entirely from a shortening of the interval between successive bursts. In contrast, speed of the individual response and number of responses per burst changed only negligibly. If S were running, the probability that it would either stop or continue did not differ appreciably for the conditions of continuous or limited access to the wheel. But if S were not running, the probability that it would start running was appreciably greater for limited than for continuous access.

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A multiple schedule having both an appetitive and an avoidance component was maintained in two dogs to create a complex behavioral base line for observing the effects of chlorpromazine. Both soluble and “Spansule” chlorpromazine generated similar functions relating drug dose to measures of behavioral output. Although the dose ranges and the drugging procedures differed markedly for the different preparations of CPZ, the functions generated were comparable. There was no evidence that chlorpromazine had a differential depressing effect as a function of type of reinforcement. At low doses, rates of responding on the food‐reinforced components increased slightly, whereas rates on the avoidance components remained relatively unchanged. At higher doses, both components showed an approximately equal depression of responding. These results are discussed with reference to some of the logical and experimental difficulties inherent in making comparisons across components of a multiple schedule and across schedules in general.

Two procedures were used in an investigation of the effects of deprivation upon counting and timing. Under the first procedure, fixed minimum interval (FMI), the rat received liquid reinforcement every time it pressed bar B after having waited a minimum of 5 sec following a press on bar A. Under the second procedure, fixed consecutive number (FCN), reinforcement was delivered every time the rat pressed bar B following a run of at least four consecutive responses on bar A.Water deprivation was varied over a set of values ranging from 4 to 56 hr. Deprivation had almost no effect on the waiting time in the FMI procedure, or on the number of responses per run in the FCN procedure. With both procedures, increasing deprivation shortened the pause between reinforcement and the next response. In the FCN procedure, the speed with which the runs were executed increased with increasing deprivation, although the number of responses in these runs was relatively unaffected.

Each of nine Ss was run for 11 daily sessions. Except for the first (operant level) and last two (extinction) sessions, 500‐ohm drops in skin resistance were followed by reinforcement (light). These reinforcement periods lasted 20 min and were preceded by 10‐min control periods during which no reinforcement was administered. Although the results showed no evidence for operant conditioning of the GSR, they did indicate that increased emission of GSR's occurred during the reinforcement period. This effect was shown to hold for Ss with low operant levels of GSR's but not for Ss with high operant levels.

Three adult, food‐deprived rats were given IP injections of dl‐amphetamine sulfate under DRL and concurrent VI DRL reinforcement schedules. The drug results were as follows. The IRT distributions of DRL responses shifted to the left, but some temporal discrimination remained. The IRT distributions of VI responses shifted slightly to the left. The distinguishing characteristics of VI and DRL IRT distributions were preserved. The frequency distribution of number of VI responses between two consecutive DRL responses was relatively unaffected. (5) Over‐all response rates on the two components of the concurrent schedules increased more or less proportionately. These findings imply that the primary behavioral effect of dl‐amphetamine was a motor excitatory one. The drug's disruption of timing behavior was not due to a derangement of internal timing mechanisms, nor to interference with the topography or pattern of behavior. Rather, it might be a secondary result of the accelerated emission of overt behavior patterns mediating the temporal spacing of DRL bar presses.