Arithmetic difficulties in children with visuospatial learning disability (VLD).

Eighteen children with visuospatial learning disability (VLD) were compared to normal control children on a series of numerical and calculation tasks. Oral and written (dictated) calculation was assessed and operations differed not only in terms of the type of number processing requirements but also in terms of their visuospatial demand. The aim was to disentangle errors due to visuospatial processing failure from those deriving from incorrect knowledge of calculation procedures. Results showed that all children had relatively good knowledge of numerical facts and there was no statistical difference between the groups. No group difference was found in the overall performance in oral calculation, but a significant difference was present when the children were required to complete the operations in writing, with the VLD group achieving poorer performance than the controls. Furthermore, VLD children had greater difficulties when operations required borrowing or carrying; this was particularly problematic in subtractions. The results indicate that VLD children do not have a generalised problem with calculation per se or number manipulation in general. Rather their problems concern dealing with some processes that govern calculation especially those loading on visuospatial abilities.