Development of Communicative Functions in Normal Persian-speaking Children from 12 to 18 Months of Age: A Longitudinal Study

 Communication can affect the personal and social life of people. According to International Classification of Functioning, Disability and Health (ICF), communication is one of the most important components of social participation and can have different functions such as behavior regulation (regulating the behavior of others to achieve a particular goal), social interaction (drawing attention of others to the self) and joint attention (attracting the attention of others to an event or particular object). Having knowledge of the development of communicative functions is so important in assessment, diagnosis, prognosis, and early intervention. Despite the importance and effect of communicative functions in language and communication development, no study has been conducted yet that examines the communicative function development of normal Persian-speaking toddlers. The purpose of this study was to investigate the development of communicative functions in normal Persian-speaking children from 12 to 18 months of age, regardless of communicative expressions (such as gestures, vocalization, and words).

This is a longitudinal observational study. The communicative function of 11 monolingual Persian-speaking 12-month-old children (7 boys and 4 girls) living in Tehran, Iran was investigated for 7 months. Sampling was done by using purposive and snowball non-probability sampling methods. All children had healthy medical history and normal growth, were from a family with a moderate socioeconomic status, and their parents had at least a high school diploma. The participants’ developmental status was assessed by Ages and Stages Questionnaire. A demographic form with acceptable content validity was also used to determine their demographic characteristics. For 7 months (once a month, each session for one hour), the examiner filmed the child-mother interaction during a semi-structured play with a set of toys at the child’s home. Afterwards, the recorded videos were coded according by the researcher and then entered into the SPSS V. 22 software. Descriptive statistics including mean and standard deviation were used to describe the data. The Shapiro-Wilk test was used to determine the normality of data distribution, and repeated measures ANOVA (within-subject comparison) was used to analyze the data. Two raters were taught about the coding and rating of the communicative functions. To verify the validity of the data coding, 20% of the recorded samples were given to them to code communicative functions. The coding validity was determined by calculating the Intra-class Correlation Coefficient (ICC).

 The mean frequency of behavior regulation and social interaction was constant from 12 to 18 months of age (P<0.05), while the mean frequency of joint attention was constant from 12 to 15 months of age (P<0.05) and then significantly increased at months 16 (P= 0.019), 17 (P= 0.023) and 18 (P= 0.003) compared to the 12th month. The ICC value as the criterion for coding validity was reported 90%.

 The mean frequency of joint attention increased significantly from 12 to 18 months of age, while it was constant for behavior regulation and social interaction. Our findings are consistent with the ICF’s social participation, stating that a child uses a particular type of communicative function to increase its participation in the society.