A dissociation between addition and subtraction with written calculation

Neuropsychologia. 1994 Jun;32(6):717-28. doi: 10.1016/0028-3932(94)90031-0.


A patient with a severe dyscalculia and a mild arabic number dyslexia is described. He could perform simple addition and subtraction sums with oral presentation. However with written arabic number sums he was impaired with addition but not with subtraction. These findings require modifications to current models of arithmetic processing which have suggested that numerical inputs are converted into abstract internal representations before arithmetical processing can occur.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / psychology*
  • Glioma / diagnostic imaging
  • Glioma / psychology*
  • Humans
  • Male
  • Mathematics*
  • Mental Processes / physiology*
  • Neuropsychological Tests
  • Occipital Lobe / diagnostic imaging
  • Parietal Lobe / diagnostic imaging
  • Reaction Time / physiology
  • Tomography, X-Ray Computed