Selective interference with the maintenance of location information in working memory.

Abstract

In 3 experiments, the nature of the events that interfere with spatial working memory was examined in order to clarify the roles of imagery, attention, and other processes in the short-term maintenance of location information. Looking and pointing at secondary task stimuli selectively interfered with memory for the locations of primary task stimuli. Secondary tasks that involved either mentally rotating primary task stimuli or making color or shape discriminations about primary or secondary task stimuli interfered with spatial working memory only if the required response was visually guided, but not if the response was verbal. Taken together, these findings support P.S. Goldman-Rakic's (1987) hypothesis regarding multiple representational domains and are consistent with known properties and connections of neurons believed to subserve the perception and maintenance of spatial information. A working memory task may be defined as one that requires holding onto information for a short time while it or other information is processed. Baddeley has proposed that there is a working memory system, specialized for concurrent storage and manipulation of information that is engaged by such tasks (for a recent overview, see Baddeley & Hitch, 1994). On the basis of studies of both intact and brain-damaged subjects (for a review, see Gathercole, 1994), Baddeley and his colleagues have divided the working memory system into three components: a phonological store for verbal information, a visuospatial sketchpad for visuospatial information, and a central executive that directs activities involved in manipulating and maintaining information in the two specialized stores. Perhaps the most studied example is the role of covert articulatory rehearsal in refreshing information in the phonological store. Performing a secondary task that requires articulation of verbal material decreases verbal memory span, a finding consistent with the hypothesized role of subvocalization in maintaining verbal information (e.g., Baddeley, Lewis, & Vallar, 1984). Much of the supporting evidence for the visuospatial component of Baddeley's model also comes from studies that use dual task procedures. These studies were designed to determine whether visuospatial and verbal working memory involve separate resources, and they have demonstrated that secondary verbal tasks interfere with memory for verbal information to a much greater extent than they interfere