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Pairs of subjects could either cooperate or respond on a lower paying individual task. Whenever both subjects chose to cooperate, either subject could make a response that took $1.00 of the other's earnings. In Exp. I, a stimulus signalled when a “take” response had been made. Either subject could avoid the loss by switching to the individual task within 5 sec after the stimulus appeared. Rates of cooperation were high when losses could be avoided but decreased again when the avoidance condition was removed. In Exp. II, a response prevented “takes” from occurring for a specified time interval after the response. This procedure also maintained cooperation. When each avoidance response subtracted from earnings, both avoidance responding and cooperation were eliminated.

Responses on a lever by rats postponed scheduled timeouts, or periods during which the delivery of response‐independent food was withheld. The effects of a number of experimental variables were examined and the conclusions drawn are that the functional relations describing free‐operant avoidance of timeout from response‐independent reinforcement are similar to those for avoidance of electric shock and that both phenomena are sensitive to the same parametric manipulations. Results suggest that high frequency of food delivery in timein maintains a higher rate of timeout avoidance than low frequency. The evidence argues against an interpretation in terms of adventitious food‐reinforcement of the timeout avoidance response. Finally, the effects of scheduling timeouts independently of responding and of omitting timeouts confirm the view that timeouts can be aversive and may act as punishment for responding.

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Four pigeons received pre‐training that included presentation of the reinforcer independently of behavior and then baseline training on a variable‐interval schedule of reinforcement. With the introduction of a multiple schedule, in which the first stimulus was associated with a response contingent and a second stimulus with a response independent, 1‐min variable‐interval schedule, a reduction in response rate was obtained in the second component, which was not accompanied by a behavioral contrast effect in the first component. A further three pigeons were given the same pre‐training and baseline training before the introduction of an otherwise identical multiple schedule, in which no reinforcement occured in the second component. Behavioral contrast was obtained from all three subjects. The results indicated that under conditions of constant reinforcement density a reduction in responding is not a sufficient condition for the occurrence of behavioral contrast.

For four pigeons key‐peck responding was reinforced on a variable‐interval reinforcement schedule in the presence of a vertical white line. When response rates had stabilized a horizontal white line was introduced, in the presence of which reinforcement was not available (extinction). The horizontal line was presented once per session, immediately before the vertical line was presented. The duration of the horizontal line varied randomly from session to session, being either 0 sec (i.e., no presentation), 10 sec, 30 sec, 2 min, 10 min, 40 min, or 120 min. When the horizontal line was present for more than 0 sec, behavioral contrast was obtained in the presence of the following vertical line. Contrast increased with increasing durations of the horizontal line, asymptoting when the horizontal line was present for 40 min.

Daytime incontinence is a major problem for retarded children. A training procedure for eliminating this problem should be facilitated by an apparatus that provided the trainer with an immediate signal when the child voided so that the trainer could react immediately. Two apparatuses were developed for this purpose: a toilet‐chair apparatus to signal proper toileting and a portable pants‐alarm apparatus to signal wetting of the pants. A reprimand was given when pants wetting occurred whereas positive reinforcement was given for proper toileting. Results with four profoundly retarded children indicated the reliability of the apparatuses in practice and the effectiveness of a toilet training program that used the two apparatuses.

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