A series of three experiments is reported that have examined how the specia
list components of the working memory model (Baddeley, 1986; Baddeley & Hit
ch, 1974) are involved during the performance of mental synthesis. The resu
lts indicate that the spatial manipulation of material during synthesis dra
ws on the resources of spatial working memory, whereas the maintenance of v
erbal representations can play an important role in making effective use of
cognitive resources during the task as a whole. These results are interpre
ted within the framework of a revised model of visuo-spatial working memory
, in which the specialist components act as temporary storage buffers for v
isuo-spatial and verbal material, whereas the generation and maintenance of
conscious visual images is primarily seen as being a function of the centr
al executive component.