Receptive vocabulary analysis in Down syndrome

Area of Science:

• Linguistics
• Developmental Psychology
• Neuroscience

Background:

• Receptive vocabulary, particularly verb knowledge, is crucial for syntactic development.
• Down syndrome (DS) and non-specific intellectual disability (ID) present unique challenges in language acquisition.
• Understanding specific lexical knowledge patterns can inform targeted interventions.

Purpose of the Study:

• To compare receptive verb, noun, and attribute knowledge in individuals with DS, ID, and typical development (TD).
• To investigate the relationship between verb knowledge and phonological memory in these groups.
• To identify distinct lexical profiles associated with DS and ID.

Main Methods:

• Fifty participants with DS (10-21 years), 29 with ID (10-21 years), and 29 with TD (4-9 years) participated.
• Receptive vocabulary was assessed using the PPVT-4, focusing on noun, verb, and attribute items.
• Nonverbal ability (Leiter-R) and phonological memory (CTOPP Nonword Repetition) were also measured.

Main Results:

• Participants with ID outperformed both DS and TD groups on verb items, independent of overall vocabulary and phonological memory.
• DS and TD groups demonstrated similar lexical patterns, favoring nouns over verbs and attributes.
• The ID group showed comparable performance on nouns and verbs, but weaker performance on attributes.

Conclusions:

• Individuals with ID exhibit a distinct receptive vocabulary profile compared to DS and TD groups, with notable strength in verb knowledge.
• Verb knowledge in DS appears to follow a pattern similar to typical development, suggesting specific linguistic challenges.
• These findings highlight the heterogeneity of language development in intellectual disabilities and have implications for educational strategies.