Abstract
Six pigeons were trained under a concurrent chains procedure so that preference for fixed-interval versus mixed-interval schedules with varying numbers of component intervals could be examined. The smallest and largest intervals in the terminal links were the same value as those used by Davison (1969). Relative choice in all cases approximated the relative means of the squares of the harmonic intervals to reinforcement in the terminal links, and no effect of number of component intervals was demonstrated. Mixed-interval versus fixed-interval choice could not be predicted from extant data on fixed-interval versus fixed-interval choice.