Cross-Linguistic Influence in Igbo-English Sequential Bilingual Acquisition: A Longitudinal Study of Children in Ogun State

This dissertation presents a three-year longitudinal investigation of cross-linguistic influence patterns in children acquiring Igbo and English sequentially in Ogun State, South West Nigeria, filling a substantial gap in the study of African child bilingual language acquisition. Sequential bilingualism in which Igbo is the first acquired language and English the second is the typical acquisition trajectory for Igbo children in diaspora environments, yet longitudinal data on the developmental dynamics of this specific language pair are absent from the acquisition literature. The study tracks forty-eight children from Igbo families in Sagamu and Abeokuta from age three to age six, collecting monthly spontaneous speech samples in both languages alongside standardised language assessments administered at six-month intervals. Cross-linguistic influence is analysed across four domains: phonological transfer, morphosyntactic transfer, lexical transfer, and pragmatic transfer, using a dynamic systems theory framework that models each child's bilingual development as an interconnected developmental system. Findings demonstrate that cross-linguistic influence is bidirectional from the earliest stages of English acquisition, with Igbo tonal patterns appearing in children's English prosody and English determiner categories producing novel grammatical constructions in Igbo. Individual variation in cross-linguistic influence magnitude is significantly predicted by home language use patterns and maternal educational level. The dissertation contributes longitudinal empirical data of a type absent for any Igbo-English bilingual population. Keywords: cross-linguistic influence, Igbo-English bilingualism, longitudinal acquisition, child language, sequential bilingualism.