Time allocations of various activities under multiple schedules in pigeons

Time allocations of three pigeons' various activities (pecking, turning, preening, wing flapping, etc.) were measured under usual multiple schedules in which only key-peck response was reinforced. Positive behavioral contrast was found for both the number and the time allocation of key-peck response. Some time allocations of the other activities were inversely varied to that of key-pecks, as stated in the competition theory of behavioral contrast. However, the amount of reallocation of interim activities was not enough to complement the amount of increases or decreases of key-pecks in the unchanged component. Most of the amount of increases or decreases of key-pecks in the unchanged component was complemented with the inactive time. This result suggests that behavioral competition is not the primary mechanism for key-peck behavioral contrast in multiple schedules in pigeons. It is important to consider inactive time, which is emerged in the usual experimental setting, to clearly attribute the behavioral contrast to reallocation of time for other activities.