Abstract
A temporally defined reinforcement schedule within the tau system of classification was studied, with pigeons as subjects and with cycle length as the independent variable. As cycle length decreased, response rates increased, responses-per-reinforcement went through a maximum, while the number of reinforcements-per-session increased. The first two functions are attributed to changes in the discriminability of the tau(D) and tau(Delta) components of the cycle, while the latter seems to result from changes in the relative durations of reinforcement time and tau(Delta) time.