The effects of component presentation and baseline rates of reinforcement on behavioral contrast were examined in rats. Each rat was exposed to a series of six multiple variable-interval schedules, divided into two three-schedule series. Each series consisted of a standard contrast design (baseline phase, contrast phase, and baseline recovery phase). The presentation of multiple schedule components within these three phases varied as a function of condition. In condition one, rats were presented with the traditional strict alternation of multiple schedule components. In condition two, rats were exposed to randomly alternating multiple schedule components. Each subject was exposed to both high (VI 15) and low (VI 30) baseline rates of reinforcement. Neither component presentation nor baseline rate of reinforcement had a significant effect on behavioral contrast. Robust contrast was observed in both conditions, at both VI 15 and VI 30 baseline reinforcement rates. These results fail to support the predictions made by habituation theory. Furthermore, the presence of contrast at relatively low rates of reinforcement has implications for additivity theory. Further research is needed to determine the applicability of habituation theory to behavioral contrast.



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