An examination of the underlying nature of prosodic disturbances in right hemisphere damaged patients

The purpose of this study was to examine the underlying nature of prosodic disturbances in right hemisphere damage (RHD) patients to determine whether both affective and prepositional levels of prosody are affected by right hemisphere damage. Two hypotheses were proposed. The first hypothesis suggests that prosodic disturbances in this population are the result of an underlying inability to process affect in general so that only affective prosody is truly impaired. This hypothesis was based on the idea that the emotional deficits, flat affect, indifference, passiveness, etc., often found in the RHD population, may be more than an alteration in the person's psychological status. The second hypothesis suggests that RHD patients exhibit a primary deficit in the abi lity to process the prosodic elements of frequency, intensity and duration, so that both affective and propostional prosody are impaired. In the following study, only the first hypothesis was directly investigated. Two tasks were utilized to examine the ability of five RHD, five LHD, and five nonneurologically involved subjects to comprehend affect. The first task, an auditory task, examined comprehension of affective prosody conveyed in neutral sentences that varied in terms of emotional tone. The second task examined comprehension of affect conveyed in visual stimuli.. A significant difference was found in the performance of the RHD group as compared to both the LHD and normal control groups. In general, the RHD group performed significantly poorer than the other groups on tasks testing comprehension of affective prosody in auditory stimuli and nonlinguistic affect conveyed in visual stimuli. Further examination of the results revealed a significant relationship in the ability to perceive affect in speech and affect in general. These findings would suggest that prosodic disturbances in RHD patients result from a more global inability to process affect which in turn restricts the ability to process the emotions which affective prosody is suppose to convey. The results also provide an additional argument against a right hemisphere role in the processing of propostional prosody. The implication of this investigation is that prosodic disturbances resulting from RHD may not be related to the linguistic nature of the task, as once was suspected, but instead, maybe related to the emotional nature of the task.