Performances on Short-Term and Working Memory Tasks and Their Relationships to Aphasia Severity and Auditory Comprehension in Normal Elderly Adults and People with Aphasia

Sung, Jee Eun

ORIGINAL ARTICLE

Commun Sci Disord. 2010;15(3): 285-297.

Jee Eun Sung^`

성지은(Jee Eun Sung)

ABSTRACT

Background & Objectives
Short-term memory and working memory capacities have gained considerable attention as underlying cognitive mechanisms, which may account for language processing difficulties in people with aphasia. However, there are limitations to the employment of short-term and working memory tasks for assessing normal cognitive processing in order to evaluate language-impaired clinical populations. The current study investigated 1) the performance differences between people with aphasia and normal elderly adults in short-term memory and working memory tasks when the stimuli modality was manipulated using digits and words and 2) how their performances on the memory tasks were related to aphasia severity and sentence processing.
Methods
Twenty people with aphasia and 30 normal elderly adults participated in the present study. Digit forward and word forward span tasks served as short-term memory tasks, and digit backward and word backward span tasks served as working memory tasks. Porch Index of Communicative Ability (PICA) was used as a measure of language impairment severity, and the Computerized Revised Token Test (CRTT) was a measure of sentence processing.
Results
Both groups showed greater difficulties in working memory tasks than short-term memory tasks and those involving words compared to those involving digits. The greatest group differences were found in the digit backward span task. Principal component analysis of four span tasks revealed that a one-factor solution accounted for approximately 80% of the total variance in both groups, indicating that the four span measures served as a unified index of the underlying memory-related cognitive mechanism that is responsible for maintaining and manipulating information. Among the four span measures, the digit forward task significantly predicted aphasia severity and sentence-processing abilities in people with aphasia.
Discussion & Conclusion
Results were partially consistent with the working memory capacity theory. Korean versions of short-term and/or working memory span tasks need to be developed in order to investigate the underlying cognitive mechanisms responsible for language impairments in aphasia. (Korean Journal of Communication Disorders 2010;15;285-297)