Working memory plays an essential role in complex cognition. Everyday cognitive tasks – such as reading a newspaper article, calculating the appropriate amount to tip in a restaurant, mentally rearranging furniture in one's living room to create space for a new sofa, and comparing and contrasting various attributes of different apartments to decide which to rent – often involve multiple steps with intermediate results that need to be kept in mind temporarily to accomplish the task at hand successfully. “Working memory” is the theoretical construct that has come to be used in cognitive psychology to refer to the system or mechanism underlying the maintenance of task-relevant information during the performance of a cognitive task (Baddeley & Hitch, 1974; Daneman & Carpenter, 1980). As reflected by the fact that it has been labeled “the hub of cognition” (Haberlandt, 1997, p. 212) and proclaimed as “perhaps the most significant achievement of human mental evolution” (Goldman-Rakic, 1992, p. 111), it is a central construct in cognitive psychology and, more recently, cognitive neuroscience.

Despite the familiarity of the term, however, it is not easy to figure out what working memory really is. To begin with, the term working memory is used in quite different senses by different communities of researchers. In the behavioral neuroscience and animal behavior fields, for example, the term is associated with the radial arm maze paradigm.