Gonzalez, R. C., Fernhoff, D., & David, F. G. (1973). Contrast, resistance to extinction, and forgetting in rats. Journal of Comparative and Physiological Psychology, 84(3), 562-571.
http://dx.doi.org/10.1037/h0034882
Conducted 3 experiments with a total of 176 naive male albino rats, in which the depression effect decreased progressively over retention intervals ranging from 1-68 days, which were interpolated between the pre- and postshift stages of a Crespi experiment; at 68 days the depression effect was entirely absent. A 68-day interval between acquisition and extinction eliminated the inverse relationship between resistance to extinction (RTE) and amount of reward in consistently reinforced Ss. The same retention interval eliminated the spaced-trials partial reinforcement effect (PRE) but not the massed-trials PRE. Results are consistent with the views that (a) the inverse relation between RTE and amount of reward is a special case of negative contrast, (b) different mechanisms are responsible for the PRE in massed and spaced trials, and (c) the spaced-trials mechanism is negative contrast. (25 ref.) (PsycINFO Database Record (c) 2016 APA, all rights reserved)