| The purpose for this study was to determine whether a shift in language processing from the left hemisphere to the right hemisphere occurs in individuals with aphasia, and what impact this shift would have on the non-linguistic abilities of the right hemisphere. Three groups of participants were examined: a group with aphasia, a group with right hemisphere disorder, and a group of controls. Participants were administered two dichotic listening tasks and were required to make a forced-choice yes or no response as to whether auditory stimuli matched a visual stimulus. In the lexical condition, words were used, while in the environmental condition, sounds and pictures were used. The measures taken include accuracy and median reaction time for each condition in each task. Results suggested significant differences in processing styles between individuals with mild comprehension impairment (i.e., anomic) as compared to individuals with a moderate processing deficit (conduction aphasia). Individuals with anomia did not display a shift in language processing, but relied on the relatively intact left hemisphere processing centers for both linguistic and non-linguistic processing. However, the individuals with conduction aphasia demonstrated a shift of language processing from the left to the right hemisphere, along with changes in non-linguistic processing, which followed the same pattern. In these individuals, it seems that the right hemisphere is responsible for both linguistic and non-linguistic processing, which occurs in homologous areas. Results also indicated a significant difference in individuals with right hemisphere disorder as compared to individuals without brain damage and individuals with aphasia. These individuals demonstrated a reliance on the intact left hemisphere for both linguistic and non-linguistic processing. Individuals with right hemisphere disorder also displayed increased reliance on the left hemisphere for language than environmental sounds, which could suggest that the right hemisphere lexicon was impaired. |
