On the dependency of division on multiplication: Selective loss for conceptual knowledge of multiplication

► This article reports the case study of a patient, AG, affected by a progressive brain disease, who showed relative sparing of conceptual knowledge for division contrasting with an extremely severe, across the board, impairment of multiplication. ► The pattern of dissociation featured by AG has never been reported before and its existence could not, in fact, be expected on the basis of theories holding that division depends on multiplication and that is not separately represented in semantic memory. ► AG's case shows that conceptual knowledge about arithmetic consists of dissociable components and force researchers to distinguish among different components of conceptual knowledge and to consider their reciprocal relation.