Number processing and calculation in a case of visual agnosia

Pesenti, Mauro [UCL] Thioux, Marc Samson, Dana Bruyer, Raymond [UCL] Seron, Xavier [UCL]

We describe the performance of a brain-damaged subject who suffered from visual agnosia leading to major difficulties in generating and exploiting visual representations from long-term memory. His performance in a physical judgement task in which he was required to answer questions about the visual shapes of Arabic numerals reflected his agnosic problems. However, he showed no impairment in usual number processing and calculation tasks. This case shows that, despite some commonalities in number and object processing, actual numerical processes are not affected by visual agnosia and can be preserved even when fine visual processes are impaired.