Rats were trained on a 5 ft. runway for food reward. Reward was immediate if response speed was below a cutoff speed, but a delay was interposed for speeds faster than the cutoff. Cutoff times varied from 2.5 to 10 sec., and delays from 2 to 30 sec., for different groups. Speed was a decreasing function of delay of reward, and a U-shaped function of cutoff time. The percentage of response speeds below the cutoff was an increasing function of delay and a decreasing function of cutoff time. "Subjects cannot be viewed as simply minimizing their delay of reward." From Psyc Abstracts 36:02:2EL96B. (PsycINFO Database Record (c) 2006 APA, all rights reserved)