McSweeney and Weatherly (1998) argued that differential habituation to the reinforcer contributes to the behavioral interactions observed during multiple schedules. The present experiment confirmed that introducing dishabituators into one component of a multiple schedule increases response rate in the other, constant, component. During baseline, pigeons and rats responded on multiple variable interval 30-s variable interval 30-s schedules. During experimental conditions, subjects responded on the same schedule except that a dishabituating stimulus (manipulation of a light) was also presented randomly during one of the components. Constant-component responding was faster during the experimental than during the baseline conditions. This difference in responding grew larger across the session. The within-session pattern of responding was similar for the two components of each multiple schedule. Qualitatively similar results were observed for rats and pigeons. These results suggest that behavioral interactions sometimes arise from a change in reinforcer effectiveness between the baseline and experimental phases of the experiment, rather than from an assessment of reinforcer relativity (a comparison of reinforcers delivered during the two components in the experimental phase). Behavioral contrast and induction are sometimes produced by similar factors.