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Experiment I demonstrated positive behavioral contrast in rats when one of two qualitatively different reinforcers (milk and pellets) was removed from a component of a multiple schedule. The contrast effect was larger and more enduring when milk was removed. Experiment II showed that the rats spent more time on the side of a shuttle‐box on which milk was freely available than on the side on which pellets were freely available. Experiment III, a partial replication of Experiment I, failed to demonstrate the contrast effect of Experiment I. Experiment IV demonstrated contrast when two topographically distinct responses, nose‐key poking and lever pressing, were required in different components of a multiple schedule. These results extend the conditions that generate behavioral contrast in rats.

Pecks on an operant key were reinforced on either multiple variable‐interval variable‐interval or multiple variable‐interval extinction schedules of reinforcement. The stimuli that signalled the multiple‐schedule components were located on a second key (signal key), and a changeover delay prevented reinforcement of signal key‐peck—operant key‐peck sequences. No behavioral contrast was observed on the operant key, and appreciable responding to the signal key occurred during the variable‐interval component of the multiple variable‐interval extinction procedure. Peck durations on the signal key were markedly shorter than peck durations on the operant key. Moreover, most responses on the signal key occurred just after the multiple‐schedule components changed. These data support an account of behavioral contrast in terms of the summation of pecks that are separately controlled by stimulus‐reinforcer and response‐reinforcer dependencies, and suggest that the stimulus‐reinforcer dependency is responsible primarily for local contrast. In addition, the data suggest that pecks that are controlled by these two dependencies may belong to topographically different classes.

The effect of self‐management procedures on objective writing responses and on the subjectively assessed quality of children's writing was investigated. All experimental procedures were applied to each of the 37 children in a regular Grade 3 class, and 14 of these children were randomly selected for data collection. Following baseline conditions, self‐assessment plus self‐recording of writing responses was introduced. This did not increase the number of sentences, number of different action words, or number of different describing words, or improve the quality of the stories. Self‐determined and self‐administered reinforcement was added to the self‐assessment and self‐recording procedures contingent on each of the writing responses in turn. Rates of responding were substantially increased and the stories received higher subjective ratings of quality from two independent judges. An increase in on‐task behavior was correlated with self‐reinforcement of writing responses.

Three experiments evaluated whether behavioral similarity provided by an adult could serve as a reinforcer for the modelling behavior of four preschoolers. In each experiment, sessions consisted of two kinds of trials: (1) experimenter‐modelled trials, when the child's imitation of modelled motor responses was reinforced with praise and tokens, and (2) child‐modelled trials when experimenter imitation of child‐modelled responses was contingent upon the child's modelling one of three alternative responses: operation of a ball, horn, or clicker. Experiment I showed that the children consistently modelled whichever responses the experimenter imitated. Experiment II determined whether that performance was due to differences in the amount of experimenter behavior following imitated versus nonimitated child models or to experimenter imitation. Neither reducing nor increasing the amount of experimenter behavior following the children's nonimitated models altered their modelling of imitated responses. Experiment III evaluated whether experimenter imitation of child models was a reinforcer because the child's imitative responses were reinforced on experimenter‐modelled trials. In Experiment III, the children's nonimitation of experimenter‐models was reinforced with praise and tokens on a schedule of differential reinforcement of other behavior, yet they continued to model experimenter‐imitated responses on child‐modelled trials. These results indicate behavioral similarity was reinforcing, though no conditioning history through which it acquired that function was demonstrated.

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