Phonological neighbourhoods in the developing lexicon.

Area of Science:

• Child language acquisition
• Developmental psycholinguistics
• Lexical representation

Background:

• Children's developing lexicons show evidence of both holistic and segmental phonetic processing.
• Previous analyses suggested limited sensitivity to phonetic detail in early word acquisition.

Purpose of the Study:

• To investigate the density and structure of phonetic neighbourhoods in young children's expressive lexicons.
• To compare children's lexical neighbourhoods with maternal input and adult lexicons.
• To examine developmental changes in lexical neighbourhood density relative to vocabulary size.

Main Methods:

• Conducted neighbourhood analyses on the expressive lexicons of two 3;6-year-old children.
• Calculated raw counts, frequency-weighted counts, and normalized neighbourhood size (proportion of lexicon).
• Analyzed maternal input and an adult lexicon for comparison.

Main Results:

• Children's lexicons contain a higher density of phonetically similar words than previously thought.
• Lexical neighbourhoods appear denser relative to vocabulary size early in development.
• Neighbourhood density, as a proportion of lexicon size, decreases with development.

Conclusions:

• Early word learning may prioritize words with frequent sounds and combinations, leading to denser initial neighbourhoods.
• Development involves acquiring words with less frequent sound patterns, altering neighbourhood density.
• The findings challenge the necessity of positing fundamentally different lexical representations for children and adults.