title: Subtraction bugs in an acalculic patient.
abstract: We report a patient, MT, who presented a specific, though not isolated, deficit in written calculation. Despite a preserved knowledge of simple arithmetic - single-digit addition and subtraction - he failed systematically in multi-digit subtraction. The nature of errors was consistent across problems and reflected the application of a disturbed underlying algorithm. Moreover, the pattern of error observed mimies a very common finding in developmental studies on arithmetical procedure acquisition (Fuson, 1990, 1992, Young and O'Shea, 1981; VanLehn, 1986, 1990). The data suggest that, within calculation skills, syntax may exist as a system of stable, but inappropriate, rules which are independent of any underlying conceptual knowledge.
authors.affiliation: Department of Psychology, University College London.
authors.forename: L
authors.initials: L
authors.lastname: Girelli
authors.forename: M
authors.initials: M
authors.lastname: Delazer
mesh_terms: D001037:Aphasia / Q000503:physiopathology / Q000523:psychology; D001925:Brain Damage, Chronic / Q000503:physiopathology / Q000523:psychology*; D002540:Cerebral Cortex / Q000503:physiopathology; D002544:Cerebral Infarction / Q000503:physiopathology / Q000523:psychology*; D004292:Dominance, Cerebral / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D011340:Problem Solving / Q000502:physiology*