# Sequence structure in children’s speech reveals non-linear development of relations between word categories

## TL;DR

This study shows that children's speech patterns reveal how their understanding of word categories develops in a non-linear way as they gain language experience.

## Contribution

The study introduces a novel method using low-dimensional embeddings to analyze how children's grammatical knowledge evolves over time.

## Key findings

- Children's speech reflects temporary grammars that optimize information distribution in sequences.
- Shifts in semantic space show gradual alignment of lexical categories during language learning.
- Functionally ambiguous word categories play a key role in restructuring children's language.

## Abstract

Why do children learn some words earlier than others? Can children’s speech patterns reveal how their evolving models of language determine what they learn? This study presents a systemic analysis of children’s speech using low-dimensional embeddings to examine how the contextual knowledge reflected in their utterances reorganizes as linguistic experience increases. We analyzed age-stratified samples from the CHILDES database (18–36 months: n = 1,693,641 tokens; 3–6 years: n = 1,750,007; 5–12 years: n = 1,721,828) and adult speech from the SUBS2VEC subtitle corpus (n = 1,742,885). Our results suggest that the order and position of words in sequences produced by children from different age groups reflect changes in the way they represent categories of words. Rather than being ungrammatical, children’s utterances appear to be structured by temporary grammars that optimize the distribution of information in sequences. The results point to shifts in how words are organized in semantic space, reflecting the gradual alignment of lexical categories during learning; this restructuring appears to draw on functionally ambiguous (multipurpose) categories in English. These findings are somewhat counterintuitive, as they suggest that not knowing the exact meaning of words can facilitate both learning and communication.

Model-based analyses of children’s speech reveal how, as language experience increases, the information in sequences and the relations between categories reorganize in ways that maintain entropy levels across the developing grammatical system.