"This study investigated the effect on runway performance of rats of giving contrasting amounts of reward in two concurrent learning situations. Rats in the Contrast group received a large reward when run in one alley (S-super(+)) and a small reward when run in a different alley (S-super(-)), the two types of trials occurring in random alternation. Performance in S-super(+) and S-super(-) was compared with that of two control groups, one receiving a large reward and one receiving a small reward on every trial. Asymptotic performance of the Contrast group in S-super(-) was inferior to that of the small reward control group, whereas performance in S-super(+) was slightly but not significantly lower than that of the large reward control group. Thus, the effectiveness of a small reward is diminished when it occurs in a context where S sometimes receives larger rewards. These results were interpreted in terms of frustration elicited by the small reward when S expects a large reward." From Psyc Abstracts 36:04:4EL96B. (PsycINFO Database Record (c) 2006 APA, all rights reserved)