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For two pigeons, behavior was compared in equivalent two‐link chained and tandem schedules in which 100 responses were required for food reinforcement but the responses required in the two links of the chained schedule were varied over the values 2–98, 50–50, and 98–2. Initial pausing, response rate in each link, and the total time to complete each ratio were recorded. In chained components, initial‐link pausing (for both birds) and total time to complete the ratio (for one bird) were generally shorter when the response requirement was 2–98 than when it was 50–50 or 98–2; for terminal‐link pausing this relationship was reversed for both birds. There were also systematic changes in behavior in tandem components, and in the relationship between behavior in chained and tandem components. The results are discussed in terms of conditioned reinforcement.

In two experiments, eight rats were trained to lever press with food on a variable‐interval schedule. Bar pressing produced shock on a variable‐interval schedule in the presence of two independently presented stimuli, a light and a tone. Two rats in each experiment received alternative presentations of the light and the tone and were consequently always in the presence of a stimulus that signalled variable‐interval punishment. The other two rats in each experiment were treated similarly except that they received periods in which neither light nor tone was present. During these periods, bar pressing was not punished. The two stimuli that signalled punishment were then presented simultaneously to evaluate the effect of stimulus compounding on response suppression. The subjects trained without punishment‐free periods did not show summation to the compound stimulus; the subjects trained with punishment‐free periods showed summation of suppression. The major difference between the two experiments was the longer mean interval of variable‐interval punishment used in the second experiment. This manipulation made the summation effect more resistant to extinction and thus increased its magnitude.

The magnitude and variability of conditioned suppression of bar pressing and dipper licking were compared. In two steady‐state experiments, suppression of bar pressing was more profound and more stable from day to day. The two measures of suppression were uncorrelated as indexed by Pearson product‐moment correlation coefficients computed for adjacent trials. Correlations within measures (internal consistency) were somewhat higher for the bar‐press system except when a high proportion of rats completely suppressed on one of the correlated trials. In a transient state experiment in which possible adventitious punishment of both response systems was eliminated, suppression of bar pressing was again more profound and considerably slower to extinguish.

The effect of contingent tangible and social reinforcement on academic performance was investigated in an experimental classroom of 25 selected underachieving students. Measures were taken of both teacher and child behavior during a baseline and two experimental treatment periods. During Treatment I, a point system with tangible backup reinforcers was combined with contingent social reinforcers dispensed by the teaching staff to assess the effects on three measures of academic performance (i.e., per cent of time at work, work output per minute, and accuracy). During Treatment II, the contingencies for the tangible reinforcers were terminated while social reinforcement was continued to see if the positive effects of Treatment I on academic performance would persist. The results show that with combined tangible and social reinforcers, students' work time, rate of output per hour, and accuracy in all activities substantially increased. After termination of the tangible reinforcers, the students maintained their high rates of ouput per hour and accuracy for the remaining period of the study while the total amount of time at work returned to the baseline level.

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Subjects could either cooperate or respond on a lower‐paying individual task. In Exp. I and II, either subject could make a response that took $1.00 of the other's earnings whenever subjects chose to cooperate. The two experiments differed as to whether taking responses were effective continuously or intermittently. Both experiments showed that the opportunity to take disrupted cooperative behavior. Experiment III indicated that if taking was possible regardless of whether the subjects cooperated or responded on the individual task, subjects either cooperated or terminated the experiment.