The other side of the coin: Cognitive properties of nonreward.

In this comment, I examine Amsel's theory in the light of rats' reaction not to frustrative non-reward per se, but to the more complicated case in which frustrative nonreward is part of a rule-based sequence of reward quantities. The discussion goes beyond Amsel's emphasis on dispositional memory to consider cognitive and representational memory-the signaling properties of reinforcement and nonreinforcement. The strengths and weaknesses of Amsel's theory are discussed with the fresh perspective that this viewpoint provides, and some issues emerge that may be fruitful for further study.