Abstract
Western Aphasia Battery (Japanese edition, 1986) and a calculation test were administered to 50 aphasic patients. The severity of aphasia and the degree of calculation disorder were found to have a signsificant positive correlation. However, apart from the average population, there were two types of patients who demonstrated severe language disorder but relatively less impaired calculation ability, and vice versa.
The two group's performance on calculation tasks and aphasia subtests were arranged in a correlation matrix. Non-verbal intellectual ability was found to be the most significant factor affecting calculation ability, followed by auditory comprehension and reading comprehension.
The identical calculation problems, which were designed to be simple for normal adults, were administered in three modes: verbal calculation, written calculation, and multiple choice format conveyed in a verbal and written mode. The patients' performance levels varied depending on the language modalities used for the task. This seemed to be due to the involvement of language competence at the phase of decoding the problem and the phase of the formation of the response. These observations suggest that the calculation inability of aphasics is a combination of non-verbal intellectual dysfunction and language disorder.
