Characteristics of Swahili–English bilingual agrammatic spontaneous speech and the consequences for understanding agrammatic aphasia

Most studies on spontaneous speech of individuals with agrammatism have focused almost exclusively on monolingual individuals. There is hardly any previous research on bilinguals, especially of structurally different languages; and none on characterization of agrammatism in Swahili. The current study identifies the features of Swahili agrammatic narrative and spontaneous speech, and compares the use of verb inflections for tense and time reference in English and Swahili in six bilingual agrammatic speakers and 12 non-brain-damaged speakers matched on age, native language and education level to the agrammatic speakers. The results show a remarkable similarity between the agrammatic phenomena in both languages on the typical agrammatic features: utterance length and speech rate are reduced and the proportion of grammatical sentences and complex sentences is lower than normal. Analysis of verb inflection demonstrates that there are no qualitative differences between the Swahili and English samples: in both languages reference to the past is more impaired than reference to the present. However, the use of verb inflection in general is better preserved in Swahili than English. English verb inflections are frequently omitted, whereas Swahili verb inflections are substituted.The implications of these findings for theories on agrammatism are discussed.

► The features of Swahili agrammatic narrative and spontaneous speech are identified.
► The use of verb inflections for tense and time reference in English and Swahili is compared.
► The results show similar patterns of impairment in both languages.
► The use of past verb forms are largely reduced compared to the use of present verb forms.
► Reference to the past is discourse linked, hence difficult for agrammatic speakers.