LEARNING WHEN REWARD IS DELAYED - MARKING HYPOTHESIS

In 4 experiments, male or female PVG hooded rats were trained on spatial discriminations in which reward was delayed for 1 min. Exp I tested B. T. Lett's hypothesis that responses made in the home cage during the delay interval are less likely to interfere with learning than responses made in the maze. Experimental Ss were transferred to their home cages during the delay interval, and controls were picked up but then immediately replaced in the maze. Contrary to Lett's hypothesis, both groups learned. Further experiments suggested that handling following a choice response was the crucial variable in producing learning: No learning occurred when handling was delayed (Exp II) or omitted (Exp III). One possible explanation for the fact that handling facilitated learning is that it served to mark the preceding choice response in memory so that Ss were then more likely to recall it when subsequently reinforced. In accordance with this interpretation, learning was found to be just as strong when the choice response was followed by an intense light or noise as by handling (Exp IV). The implication of marking for other phenomena such as avoidance, quasi-reinforcement, and the paradoxical effects of punishment is also discussed. (20 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1979 American Psychological Association.