Symmetrical and asymmetrical coding of food and no-food samples in delayed matching in pigeons.

Abstract

The finding that retention functions decrease more rapidly on trials initiated by a food sample than on trials initiated by a no-food sample was replicated. This result was also obtained for samples that do not contrast hedonically , but that are characterized by the presence versus absence of an event. These results are consistent with an asymmetrical-coding model in which it is held that (a) a no-food sample is not coded, (b) responding to the comparison associated with a no-food sample occurs as a default, and (c) the default response is overridden by the presence in working memory of a code activated by the presentation of food