THE ROLE OF VISUOSPATIAL WORKING-MEMORY IN THE MENTAL ADDITION OF MULTI-DIGIT ADDENDS

A series of experiments examined the role of visuo-spatial working mem ory in the solution of mental addition problems. For this purpose a st andard task was devised in which subjects were required to mentally su mmate two 3-digit addends presented either visually or auditorily. Exp eriment 1 demonstrated that during mental addition both spatial interf erence and articulatory suppression were each capable of disrupting th e working storage of initial problem information. While visual interfe rence failed to disrupt performance in zero-carry problems, when the w orking retention of partial results and carrys was examined, evidence of selective interference was found. Here the disruption produced by a rticulatory suppression was found to be limited to the storage of inte rim results while the disruptive effects of spatial and visual interfe rence were confined to the retention of carry information. Experiment 2 examined the nature of the spatial organization of problem material within working memory. Results were consistent with the findings of Ha yes (1973), suggesting that problem digits are represented on the VSSP in a columnar spatial arrangement. A third experiment investigated th e role of visual processing in the working storage of problem informat ion. A visual similarity effect was found indicating the presence of v isual coding during the working retention of initial problem material. It was concluded that collectively the present results converge on th e view that mental addition involves the deployment of a working memor y constellation in which both the VSSP and the articulatory loop parti cipate. The loop appears to be responsible for the working storage of partial results and also contributes to the retention of initial probl em information. The VSSP functions as a mental blackboard upon which m aterial may be visuo-spatially represented whilst various operations a re performed upon it.