Hierarchical structure in a self-created communication system: Building nominal constituents in homesign

Area of Science:

• Developmental linguistics
• Sign language studies
• Cognitive science

Background:

• Deaf children with severe hearing loss, lacking spoken language and sign language exposure, develop homesign systems for communication.
• Homesigners utilize gestures, including demonstratives (e.g., 'that') and category points (e.g., 'bird'), to refer to entities.
• Previous research established the referential capabilities of individual gestures in homesign.

Purpose of the Study:

• To test the hypothesis that homesigners combine different gesture types to form larger, multi-gesture nominal constituents.
• To investigate if these multi-gesture units function similarly to single gestures in referring to entities.
• To explore the emergence of hierarchical constituent structure in homesign without conventional language models.

Main Methods:

• Longitudinal analysis of gestural communication data from a homesigner named David.
• Examination of gesture combinations, specifically focusing on the co-occurrence of demonstratives and noun-category gestures.
• Semantic and syntactic functional analysis of multi-gesture units compared to individual gestures.

Main Results:

• David's homesign system demonstrated the combination of demonstrative gestures and noun-category gestures to form multi-gesture nominal constituents (e.g., 'that bird').
• These multi-gesture units served equivalent semantic and syntactic functions to individual demonstrative or noun gestures.
• The larger units substituted for smaller units, functioning as cohesive nominal constituents within his communication system.

Conclusions:

• Homesigners can create complex nominal constituents by combining different gesture types, indicating an innate capacity for hierarchical structure.
• This finding supports the hypothesis that children can develop sophisticated linguistic structures even in the absence of a conventional language model.
• The study highlights the flexibility and generative potential of homesign systems in early language acquisition.