Syllable frequency effect in speech production: evidence from aphasia

In this study, we investigated whether a syllable frequency effect can be observed in aphasic speakers with a phonological encoding impairment. First of all, we analysed the substitution errors from seven aphasic subjects comparing the frequency of the target syllable to the frequency of the produced syllable. A significant effect of syllable frequency was observed on three subjects' errors and this effect was independent of phoneme frequency in two of them. Secondly, we examined whether syllable frequency can affect the production accuracy on a non-word repetition task. Two aphasic subjects produced significantly more correct responses to non-words composed of high frequency than of low frequency syllables. Finally, syllable frequency was manipulated in monosyllabic words and we analysed the performance and the errors of a single case aphasic subject producing phonemic paraphasias on monosyllabic words. No syllable frequency effect was observed on performance, but a syllable frequency effect arose in the error analysis. Taken together, our results provide evidence for a syllable frequency effect in some aphasic subjects with phonological encoding disorders, supporting the idea of a representation of syllables in speech production.