The Effect of Verbal Prosody on Speech Perception in Adults With and Without Down Syndrome

Abstract

<p> Emotion perception in speech has been shown to facilitate greater understanding and learning in adults as well as children. There is an atypical RH specialization for speech perception that exists in individuals with Down Syndrome (DS). Individuals with DS have a typical left hemisphere specialization for motor control and speech production, similar to those individuals from the general population which may cause a functional dissociation between speech perception and motor control for these individuals (Heath et al., 2000). What remains unknown is how this atypical lateralization may influence speech perception when emotional intonation is included with verbal stimuli. Using a free recall dichotic listening paradigm, it was found that individuals with DS process verbal stimuli similarly to mental-age matched peers (individuals with a developmental delay, and individuals for the general population.) To investigate this further, a directed attention paradigm was employed. Participants listened to a particular ear for either a particular word or emotion. It was found that individuals from the general population were more accurate than individuals from either of the other two groups for perception of the word. Also, an effect for Ear was found with the right ear being significantly more accurately perceived than the left for all three groups. When emotion was attended to specifically, the left ear was more accurately perceived than the right. These results are somewhat consistent with previous findings (e.g., Bulman-Fleming & Bryden, 1994) for participants from the general population however the expected lateralization in DS group was not evident. This lack of atypical RHA in individuals with DS may be related to the task itself.</p>