Separation of the systems for color and spatial manipulation in working memory revealed by a dual-task procedure.

The manipulation of different kinds of content is fundamental to working memory. It has been suggested that the mere maintenance of color and spatial information occurs in parallel, but little is known about whether this holds true for manipulation as well. Using a dual-task delayed-response paradigm that required the manipulation of color and angles, this study finds that the two functions do not interfere. Conversely, interference did occur when both components of a dual-task tapped into the spatial system. Thus, color and spatial information are manipulated in parallel. A concurrent phonological task did not interfere with either maintenance or manipulation, whereas a task requiring central executive processes interfered with manipulation only. We speculate that the ventral-dorsal dissociation of visual processing is conserved for manipulation processes and that manipulation differs from maintenance in the extent to which is relies on central executive resources.