ABSTRACT
Under appropriate conditions, many adults show impressive problem-solving skills, as indicated by their ability to learn algebra, assemble toys from instructions, or devise plans for a complex event, such as moving a household. In spite of these impressive problem-solving skills, it is neither difficult nor surprising to demonstrate that under some circumstances, these same adults can appear much more limited in their problem-solving skills. Hesitations and errors are easily evoked even in familiar tasks like mental arithmetic or syllogistic reasoning when they exceed the problem solver's ability to compute and maintain information online, without the aid of pencil and paper. Errors in such reasoning tasks are often accepted as manifestations of the limitation of short-term or working memory. In this chapter, we examine in detail the processes that fail in one type of reasoning task in order to characterize the underlying limitation on working memory. We describe a range of cognitive phenomena that indicate performance constraints, phenomena such as a limit on how much information can be stored in a given situation, or on how fast it can be processed. We present an integrated account of these phenomena in terms of a unified theory of capacity constraints (or resource limitations) in cognition.
