Expressive Vocabulary Development of a 15-34-Month Persian Speaking Child: A Longitudinal Case Study

Some of the models in the evaluation of speech and language disorders have been based on the sequence of language development. Developmental-descriptive model supports the approach of following the sequence of natural language as the best training manual for teaching language to children who have a language disorder. The present study aims to investigate expressive vocabulary and lexical development of a Persian speaking child aged between15 to 34 months.
Case Report: In the current observational longitudinal study, expressive vocabulary and lexical output of a Persian speaking girl sampled from 15 to 34 months by daily scripting.

The first meaningful word was stated at the age of 15 months. Since about 22 months of age, when the vocabulary storage contained about 55 words, the child started to produce grammatical structures in the form of two-word sentences. In this period, names had the most frequency in child's lexicon. At 22 months of age, the highest frequencies of her vocabulary included names of persons, foods, objects, body parts, clothing and animals, respectively. The emergence of new verbs showed a remarkable growth at the age of 26 to 28 months. In this stage, the child started to use compound sentences. Scripting and evaluating the development of the child's vocabulary every 15 days showed vocabulary spurt at the age of 26 to 28 months.

According to the results, the present 20-month longitudinal study showed that the development of expressive vocabulary in the Persian speaking girl was similar those in other languages. It also follows a hierarchical process from simple to sophisticate. This information can hopefully provide useful evidence for clinical research and practice.