Preference for fixed-interval schedules: effects of initial-link length.

Six homing pigeons were trained on a variety of concurrent-chains schedules in which the initial links were equal variable-interval schedules and the terminal links were fixed-interval schedules. Both terminal-link and initial-link schedules were systematically varied. The results showed that preference for a particular terminal-link schedule combination was greater, the shorter the initial-link schedules. The data closely matched predictions from the model of choice suggested by Davison and Temple (1973), but did not match predictions from two other models. An alternative method for analyzing concurrent-chains performance by assuming that the schedule consists of both chained schedules and successive, discriminated components that comprise multiple schedules, was suggested.