"1. Five groups of white rats with delays of reward of 0, 5, 15, 45, and 120 sec. were run in a simple T-maze under conditions which eliminated differential stimulation in the delay chambers following correct and incorrect choice." Differential external stimuli were present during the delay period for a 45-sec. control group. 2. The rate of learning of this control group was significantly superior to that of the corresponding experimental group. 3. The results from the five experimental groups showed that the shorter the delay the more rapid the rate of learning . . … 4. The three short delay groups had a negatively accelerated rate of learning, while the incomplete learning curves for the two longer delay groups were approximately linear in form. 5. The results from this and other studies were interpreted as supporting Hull's hypothesis that the range of the goal gradient is extended and its rate of fall slowed up by the effects of secondary reinforcement . . …" (PsycINFO Database Record (c) 2006 APA, all rights reserved)