What do children with specific language impairment do with multiple forms of DO?

Area of Science:

• Linguistics
• Developmental Psychology
• Child Language Acquisition

Background:

• The word 'do' serves multiple grammatical functions in English.
• Understanding how children with specific language impairment (SLI) acquire these functions is crucial for theoretical accounts of SLI.
• Early language development research often examines plurifunctional words to understand linguistic deficits.

Purpose of the Study:

• To investigate early usage patterns of the plurifunctional word 'do' in children with and without SLI.
• To analyze how children with SLI utilize different grammatical functions of 'do' compared to typically developing peers.
• To evaluate theoretical models of SLI deficits based on children's use of 'do'.

Main Methods:

• Analysis of spontaneous language samples from 89 children (37 with SLI, 37 age-matched controls, 15 language-matched controls).
• Examination of children's use of multiple functions of 'do', including auxiliary, lexical, and elliptical forms.
• Quantification of proportion correct and error types for each function of 'do'.

Main Results:

• Children with SLI demonstrated significantly lower correct usage of auxiliary 'do' compared to control groups.
• Omissions of the auxiliary 'do' form were the primary error type for children with SLI.
• Children with SLI exhibited high accuracy in using lexical 'do' and elliptical 'do', similar to controls.

Conclusions:

• The acquisition of 'do' functions by children with SLI is function-specific, not hindered by plurifunctionality itself.
• Grammatical properties, rather than surface form, determine the difficulty children with SLI face with 'do' usage.
• Findings support the extended optional infinitive account of SLI and suggest auxiliary 'do' omissions can be a clinical marker for SLI.