AMNESIA FOR ARITHMETIC FACTS - A SINGLE-CASE STUDY

We report the case of an anarithmetic patient with a selective deficit of memory for elementary arithmetic facts, who produced, for instance , ''25'' in answer to ''4 x 5.'' The patient showed good language comp rehension and production abilities, had minimal number transcoding dif ficulties, and mastered normally multidigit arithmetic procedures. She was submitted to a series of calculation, verification, and number cl assification tasks. The arithmetic deficit was evident in both recogni tion and recall tasks, was consistent across testing sessions, and did not vary as a function of the format used for presentation of the pro blems. The patient failed even when only implicit access to arithmetic facts was expected: In a timed addition verification task, she did no t show a normal inhibition effect when rejecting addition problems in which the proposed result was the product of the two operands (e.g., ' '3 + 4 = 12''). We suggest that the deficit resulted from a specific a nd permanent degradation of some connections and nodes in arithmetic l ong-term memory. (C) 1994 Academic Press, Inc.