Past research has shown that lesions in the left cerebral hemisphere
often result in aphasia, while lesions in the right hemisphere frequently
impair the production of emotional prosody and facial expression. At least
3 processing deficits might account for these affective symptoms: (1)
failure to understand the conditions that evoke emotional response; (2)
inability to experience emotions; (3) disruption in the capacity to encode
non-verbal signals. To better understand these disorders and their
underlying mechanisms, we investigated spontaneous affective communication
in right hemisphere damaged (RHD) stroke patients with aprosody and left
hemisphere damaged (LHD) stroke patients with aphasia. Nine aprosodic RHD
patients and 14 aphasic LHD patients participated in a videotaped
interview within a larger treatment protocol. Two naïve raters viewed
segments of videotape and rated facial expressivity. Verbal affect
production was tabulated using specialized software. Results indicated
that RHD patients smiled and laughed significantly less than LHD patients.
In contrast, RHD patients produced a greater percentage of emotion words
relative to total words than did LHD patients. These findings suggest that
impairments in emotional prosodic production and facial expressivity
associated with RHD are not induced by affective–conceptual deficits
or an inability to experience emotions. Rather, they likely represent
channel-specific nonverbal encoding abnormalities. (JINS, 2005,
11, 677–685.)