CONCEPTS AND FACTS IN CALCULATION

A patient is described who is affected by an inability to recall and u se 'arithmetical facts' of one-digit multiplications and divisions. Th is loss contrasts with the preservation of a wide set of complex notio ns that the patient exploits in order to overcome his deficit and get the right result. This observation helps in isolating and describing a n important component of arithmetical long-term memory that is not ove rlearnt and the functioning of which is not automatic or mechanistic. An account of such a component is lacking in models of arithmetic curr ently referred to in cognitive neuropsychology. In a remediation study , performed over several weeks, the effect of training was selective f or each single arithmetical fact: not even skills with multiplication complements (e.g. 6X3, 3x6) fully benefited from the rehabilitation of a specific fact. This suggests that the storage format of each fact i s independent from that of other facts.