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Hungry rats received food following lever‐press durations exceeding a minimum value, which ranged from 0 to 6.4 sec. When no intertrial intervals separated successive presses, modal press durations remained at very short values as the minimum value required for food was increased. This was particularly true immediately after a food presentation. When an 8‐sec intertrial interval followed each lever release, modal press durations were always at or beyond the minimum value required for food, and outcome of the preceding press had no effect on press duration. Possible reasons for the effects of intertrial intervals included punishment of short presses, increased delay of reinforcement of short presses, and reduced density of reinforcement. In addition, functions relating discrete‐trials lever‐press duration to minimum duration required for food were found to be qualitatively and quantitatively similar to the power functions recently proposed by Catania (1970) for interresponse time and response latency. This similarity was taken as support for a general psychophysical law of temporal judgments.

Four schizophrenic patients with paranoid and grandiose delusions who had been hospitalized for an average of 17 yr were exposed to social reinforcement contingencies in a multiple baseline design. During the baseline period, each patient was interviewed for four 10‐min sessions each day. The elapsed time from onset of conversation to onset of delusional talk was recorded. At the end of each day, the patients engaged in a 30‐min informal chat with a nurse‐therapist while relaxing with coffee, snacks, and cigarettes. The intervention introduced two contingencies: (1) The 10‐min interviews were terminated as soon as the patient began talking delusionally; (2) The patients earned time for their evening chat by talking rationally during their daytime interviews. Increases of from 200 to 600% in the amount of rational talk exhibited during the interviews occurred as the contingencies were introduced for each patient sequentially over time. These increases were maintained in three patients when the amount of reinforcement was halved, but declined when the patients were confronted directly with their delusional ideas. A modest amount of generalization occurred from the day‐time interviews to the evening chats but did not extend to the behavior of the patients on the ward.

The response latency of following directions by an 8‐yr‐old boy from a class for emotionally disturbed children was modified by the contingent application of a token system. To demonstrate reinforcer effectiveness, a multiple baseline approach was used. Measures were obtained for the time elapsed between the presentation of verbal directions and five performances: (1) entering the experimental room, (2) putting toys away, (3) beginning academic work, (4) putting toys away again, and (5) returning to the classroom and completing preparations for leaving school. These five measures were placed on the token system at three different times. The results demonstrated that four of the five performances were clearly affected by the token system as their response latency for following directions decreased substantially.

In three observing‐response experiments relevant to the information hypothesis of conditioned reinforcement, the basic procedure was one in which an observing response produced one stimulus on trials that terminated in non‐contingent reinforcement and another stimulus on trials that terminated in a brief timeout. In Experiment I, the observing response consisted of a single peck or a short fixed‐ratio schedule (FR 3 or FR 6), depending on the type of trial. If the single peck produced the negative stimulus and the fixed ratio produced the positive stimulus, observing responses were maintained. If the single peck produced the positive stimulus and the fixed‐ratio produced the negative stimulus, observing responses were not maintained on negative trials. In the second experiment, the response key was either white or dark at the beginning of a trial, indicating whether it was a positive or negative trial. Observing responses continued to be maintained on positive trials but not on negative trials. In Experiment III, only positive or negative trials were scheduled for several sessions. Observing responses extinguished regardless of whether positive or negative trials were scheduled. The results do not support the hypothesis that making the stimuli produced by observing responses redundant will reduce observing responses.

This study investigated possible factors in promoting racial integration, a matter of practical concern in schools today. Specifically, the effect of social and tangible reinforcement was studied on the social integration of five black children in a predominantly white classroom. “Sitting and seating with a new friend” in the school cafeteria was manipulated by (a) teacher directive combined with reinforcement and (b) by positive reinforcement alone. Treatment effectiveness was studied in the cafeteria and as generalization effects to a free‐play period. The results indicated that reinforcement produced significant generalization to integrated free play, although intersubject variability was present. Evidence suggests that reinforcement techniques can be used effectively to promote social integration.

A study was conducted concerning the frequency of litter deposits in a single experimental trash receptacle located in a high‐use, urban park setting. There were four two‐week periods of alternating no‐contingency, contingency conditions during which reinforcement and incentive were evaluated. It was found that reinforcement resulted in the highest rates of behavior and improvements in the aesthetic appearance of the area.

Pigeons' pecks on each of two concurrently available response keys were reinforced under a variable‐interval schedule that sometimes allotted food‐pellet deliveries to one key and sometimes to the other. The keys differed in the number of reinforcements assigned to each and in the number of pellets delivered during each reinforcement. When the total quantity of food associated with each key during a session was constant, the proportion of responses to a key depended on the particular combinations of reinforcer rate and reinforcer magnitude scheduled on each key. A given quantity of food generated more responding on a key when it was delivered frequently in small amounts than when it was delivered infrequently in large amounts.

Pigeons' responses on either of two concurrently available keys each associated with variable‐interval 60‐sec schedules occasionally changed the schedule on that key to a terminal‐link interval schedule providing access to gain while the other key became inoperative. Experiment I compared simple fixed‐ and mixed‐interval schedules in the terminal links, and showed that for all subjects and schedules the distribution of responses during the concurrent initial links was accurately described by the relative inverse delay of reinforcement squared. Experiment II extended the generality of this formulation to a situation in which rate of reinforcement was constant and delay alone was varied.

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Pigeons responded in a two‐key situation. Responses on the right key (food key) were reinforced with food presentation on a response‐initiated fixed‐interval schedule, (i.e., first response after a fixed period of time was reinforced); responses on the left key (target key) were reinforced on a fixed‐ratio schedule (i.e., every nth response was reinforced) with the presentation of a target bird that could be attacked. When the interval value of the food reinforcement schedule was varied from 1 min to 5 min, both the rate of attack responding on the target bird and the rate of responding on the target key were a function of the interval value. Responding on the target key was not maintained by the stimulus change associated with target availability, and was successively extinguished and reconditioned by removing and returning the target bird to the restraining box. When food was delivered independently of behavior, responding on the target key either remained unchanged or decreased, but was not eliminated. Responding on the target key was not maintained in the absence of an intermittent schedule of food presentation.