1. Bower, G. H., A contrast effect in differential conditioning. Journal of Experimental Psychology, 1961, 62, 196–199.
2. Campbell, P. E., & Knouse, S. B. Extinction following delayed reward: A review. Psychonomic Monograph Supplements, 1972, 4, 257–268.
3. Capaldi, E. J. A sequential hypothesis of instrumental learning. In K. W. Spence and J. T. Spence (Eds.) The psychology of learning and motivation. Vol. 1, New York: Academic Press, 1967, Pp. 67–156.
4. Dunham, P. J. Contrasted conditions of reinforcement: A selective critique. Psychological Bulletin, 1968, 69, 295–315.
5. Flaherty, C. F., Riley, E. P., & Spear, N. E. Effects of sucrose concentration and goal units on runway behavior in the rat. Learning and Motivation, 1973, 4, 163–175.