Journal of Childhood

Introduction
The present study investigated the level of difficulty in understanding and producing grammatical structures of Persian language among children with autism spectrum disorder compared to typically developing children. In recent decades, increasing attention has been paid to the linguistic profile of children with autism spectrum disorder, especially in relation to structural aspects of language, such as syntax and conjugation. Although pragmatic deficits are widely recognized as a core feature of autism, increasing evidence suggests that grammatical development may also be delayed or abnormal in many children with this disorder. 
Grammatical competence plays a fundamental role in academic achievement, narrative ability, and social interactions; therefore, difficulty in this area can significantly impact functional communication and educational outcomes. Persian, as an inflectional language with distinct syntactic and morphological features, provides a valuable context for investigating grammatical development in autism. Structures, such as reflexive, passive, negative sentences, and complex sentence patterns require the integration of multiple linguistic and cognitive processes. 
However, research focused on Persian-speaking children with autism is limited, and findings from studies conducted in Indo-European languages, ​​such as English cannot be directly generalized to Persian. The present study aimed to fill this gap by comparing the comprehension and production of grammatical structures between children with autism and their typically developing peers in an Iranian context, thus providing language-specific evidence that can be useful in both theoretical and applied fields. 
Furthermore, examining grammatical abilities in early childhood is of particular importance, as this period is considered a sensitive window for language acquisition and neuroplasticity. Early identification of grammatical weaknesses can pave the way for timely intervention and prevention of causative consequences in future academic and social development. Focusing on children aged 3 to 7, the present study examined a developmental stage in which basic grammatical structures are actively forming, allowing for a more accurate comparison of typical and atypical language development trajectories in Persian-speaking children.

Research Methods 
This quasi-experimental study included an experimental group and a control group. Participants consisted of 80 children aged 3 to 7 years in Tabriz in 2023, comprising 40 children with autism spectrum disorder and 40 typically developing peers. Children with autism were selected from educational and rehabilitation centers, while typically developing children were recruited from kindergartens and schools. Random sampling was conducted among eligible centers. 
To assess comprehension and expression of Persian grammatical structures, the Bilingual Aphasia Test (developed by Paradis and Libben in 1987) was used, and responses were recorded using the Test for Reception of Grammar (developed by Bishop in 1983). Data were analyzed using SPSS software. 
The inclusion criterion for the autism group was a definitive clinical diagnosis of autism spectrum disorder based on standard diagnostic methods and expert assessment. All participants had normal hearing, and no other neurological or sensory disorders were reported apart from autism. Typically developing children were also screened to ensure the absence of developmental, cognitive, and language disorders. Demographic variables such as age and educational level were controlled to ensure homogeneity between the two groups.
The assessment process was conducted individually in a quiet and familiar environment to minimize distractions and anxiety, particularly for children with autism. Each child completed the comprehension and production tasks under the supervision of a trained examiner. Instructions were presented in simple, age-appropriate language, and sufficient rest periods were provided when necessary. Scoring followed the standard criteria outlined in the test manual, and responses were coded and reviewed to ensure accuracy
Statistical analyses were performed to examine between-group differences in grammatical constructions, and an appropriate significance level was applied to determine the magnitude of the effects. To enhance the reliability of the findings, all tests were administered by a single examiner, and the scoring process was reviewed. Data were carefully entered and rechecked prior to analysis. Descriptive statistics were first calculated to summarize the performance of the two groups, followed by inferential analyses to identify significant differences between children with autism and typically developing children in various grammatical categories.
Results 
Children with autism scored lower than their peers on all grammatical measures. The mean scores for autistic children were 5.6 for binary conjunctions, 5.29 for relative clauses, 5.23 for “not only X but also Y” structures, 5.16 for negative and descriptive subject sentences, 5.01 for passive reflexive sentences, 4.6 for active reflexive sentences, and 2.4 for singular/plural nouns. Overall, the mean scores for comprehension and expression in autistic children (20.96) were significantly lower than those of typically developing children (60.04). Further analyses showed that the observed differences between the two groups were consistent across both comprehension and expression domains.
Children with autism demonstrated greater difficulty particularly in complex syntactic structures that require hierarchical processing and the integration of multiple grammatical components. In contrast, typically developing children showed stronger performance on all measured structures, indicating age-appropriate mastery of Persian grammar. The pattern of results suggests that grammatical deficits in autism are not limited to a specific construct but instead span a wide range of language forms. Although individual differences were present within the autism group, the overall trend indicates a substantial gap between children with autism and their peers, confirming the robustness of the findings.
Conclusion 
The findings indicated significant deficits in the comprehension and expression of Persian grammatical structures in children with autism. These deficits encompass a wide range of syntactic and morphological structures and emphasize the need for targeted interventions in language development. The results are consistent with previous research, suggesting that children with autism face challenges in structural areas of language in addition to pragmatic problems. The observed difficulties in understanding and producing Persian grammatical structures may be attributed to underlying cognitive factors, such as limitations in working memory, reduced processing speed, or unusual language learning mechanisms. 
Complex structures in particular place a greater burden on these cognitive resources, resulting in lower performance in children with autism. Furthermore, the findings emphasize the need to increase awareness among teachers and clinicians about the grammatical challenges of children with autism. Language interventions often focus on vocabulary and pragmatic skills, but the present results suggest that systematic attention to syntax and conjugation is equally essential. Incorporating grammar-based activities into early learning environments can contribute to more balanced language development and improve the overall communicative competence of children on the autism spectrum. From a clinical perspective, the results highlight the importance of explicit grammar instruction in speech therapy and language intervention programs. Instructional strategies should prioritize the structures that pose the greatest difficulty while also taking into account individual differences in language ability. Despite the findings, this study has limitations, including its cross-sectional nature and regional sampling. Future research could examine longitudinal patterns of grammatical development and the effectiveness of targeted interventions to improve grammatical comprehension and expression in Persian-speaking children with autism.
Ethical Considerations
Compliance with ethical guidelines
Before implementing the research protocol, the ethics code 1401.267 IR.IAU.TABRIZ.REC was obtained. This research is derived from a doctoral dissertation.
Funding
The present research received no funding and is derived from a doctoral dissertation.
Authors contributions
All authors have contributed equally to the writing of the article.
Conflicts of interest
The authors declared no conflicts of interest in relation to this study.
Acknowledgments
We hereby acknowledge and thank all those who cooperated and assisted in conducting this research, including autistic children and their families.