On some causes of behavioral contrast.

Responding at low rates was differentially reinforced in each of two components of a multiple schedule. In order to study the relative contributions to behavioral contrast in one component of the rates of responding, and of reinforcement in a second component, a series of visual stimuli correlated with the duration of each interresponse time was added to one component. The added stimuli resulted in a decreased rate of responding and hence an increased rate of reinforcement in that component. Despite the increase in the rate of reinforcement, the rate of responding without added stimuli in the other component increased (contrast), even though the increase resulted in less frequent reinforcement.