The focus of the experiments to be discussed here is working memory, particularly the manner in which working memory processes lists of items. This emphasis on multiple items is unusual (see Thompson and Herman, 1977). As indicated elsewhere in this volume by Honig (Chapter 1), most previous working memory experiments have used a delayed-matching-to-sample (DMTS) procedure in which only a single stimulus is presented as the sample. We wanted to extend the investigation of the characteristics of working memory to the representation of multiple events in working memory. Because of the difficulty animals have learning nonspatial DMTS tasks, we used a spatial maze procedure.