Behavioral contrast and induction in the crow

Common crows received baseline training on an equal-valued multiple variable-interval variable-interval schedule of food reinforcement. When the schedule was subsequently changed to a multiple variable—interval variable-time schedule, in which reinforcement was delivered independently of responding in the latter component, this resulted in negative induction. That is, responding decreased in both components. After a return to the baseline schedule, a change to a multiple variable—interval extinction schedule, resulted in decreased responding in the extinction component. Accompanying this change was an increase in responding during the unaltered variable—interval component, i.e., positive behavioral contrast. Differences between these findings and predictions derived from several theories of behavioral contrast are discussed.