According to the classical working memory perspective, tasks such as command and control decision-making should be performed less effectively if extraneous material must be retained in short-term memory. Only marginal support for this prediction was obtained for a simulation involving scheduling trucking and transportation missions, although robust memory loading did occur in the case of more abstract tasks. This pattern of results is not consistent with the classical single system view of working memory, and suggests that working memory may have multiple subsystems. Apparently, some memory demands can be isolated from the memory system used to accomplish the trucking and transportation task. Increased understanding of the nature of working memory subsystems and of isolation of task components into separate subsystems should aid in design of command and control task environments. (Two pages of references conclude the document.) (Author)