The Effects of Bilingualism on First Language Acquisition: A Focus on Grammar Development in Early Childhood

Abstract This study searches on how early bilingualism affects young children's Farsi grammatical development. Thirty participants, ages four to five, were chosen from a Tehran kindergarten and split into two groups: fifteen children who spoke Farsi only and fifteen children who were exposed to Farsi and a heritage language (either Kurdish or Azeri) at the same time. A Sentence Repetition Task (SRT) and a picture-based grammar elicitation and picture story narration task were used to evaluate grammatical proficiency. Those tasks were created to focus on fundamental Farsi grammatical features, such as verb tense, agreement, word order, and the usage of subordinate clauses and others. Parental language background data were collected via a standardized questionnaire adapted from the Language Exposure Assessment Tool (LEAT). Results showed that monolingual children scored higher than bilingual peers on most assessments of grammar, particularly those examining complex sentence structure. However, the bilingual group demonstrated comparable performance on simpler constructions. These findings support previous research indicating that reduced or uneven exposure to the societal language can affect grammatical accuracy in bilingual children, without indicating a language delay or disorder. The study investigated the importance of considering linguistic background when evaluating early grammatical development.