Interference in Oral and Written Speech of Bilinguals in Kazakhstan: Causes and Mechanisms

Abstract

Linguistic interference in the oral and written production of balanced Kazakh–Russian bilinguals within Kazakhstan’s trilingual education context are investigated in this study. Despite extensive documentation concerned with interference phenomena, prior research has rarely systematically compared modalities or integrated structural-level, directionality, and individual-difference variables within a single empirical design. The present mixed-methods study constructed a dual-modality corpus comprising 160 essays (Kazakh and Russian) and 1,600 elicited oral utterances from 80 university students in North Kazakhstan, complemented by semi-structured interviews with a stratified subsample. All texts were annotated in ELAN for lexical, morphosyntactic, phonological, and discourse-pragmatic interference, and analysed using descriptive statistics, t-tests, effect sizes, correlation analysis, and thematic coding. The results showed that the interference was significantly more frequent in oral than written production, with spontaneous speech dominated by morphosyntactic violations and phonological assimilation. In contrast, written texts demonstrated a higher proportion of lexical-semantic calques. The directionality was asymmetrical: Kazakh→Russian transfer, especially at the lexical level, exceeded Russian→Kazakh, while Russian→Kazakh interference was more prominent in morphosyntax. The advanced English proficiency was positively associated with higher Kazakh–Russian interference, suggesting a trilingual cognitive-load effect. The metacognitive awareness was associated with large drops in morphosyntactic, but deprived of phonological errors, and the L1 dominance influenced patterns of interference. The research provided a corpus-supported, theoretically integrated explanation of interference as a dynamic process of interaction among cognitive control, sociolinguistic prestige, and structural compatibility. It provides evidence-based suggestions for trilingual pedagogy and language policy regarding explicit metalinguistic training and the strict sequencing of English in Kazakh-Russian bilingual education.