# Multiplex model of mental lexicon reveals explosive learning in humans

## TL;DR

This study models the mental lexicon as a multiplex network incorporating semantic, taxonomic, and phonological relations, revealing an explosive emergence of a core word cluster around age 7 that enhances language robustness.

## Contribution

It introduces a multiplex network framework for the mental lexicon, highlighting the explosive development of a core word cluster and its role in language acquisition.

## Key findings

- Core word cluster emerges around age 7
- Cluster increases lexical navigability and robustness
- Explosive transition linked to polysemy

## Abstract

Word similarities affect language acquisition and use in a multi-relational way barely accounted for in the literature. We propose a multiplex network representation of this mental lexicon of word similarities as a natural framework for investigating large-scale cognitive patterns. Our representation accounts for semantic, taxonomic, and phonological interactions and it identifies a cluster of words which are used with greater frequency, are identified, memorised, and learned more easily, and have more meanings than expected at random. This cluster emerges around age 7 through an explosive transition not reproduced by null models. We relate this explosive emergence to polysemy -- redundancy in word meanings. Results indicate that the word cluster acts as a core for the lexicon, increasing both lexical navigability and robustness to linguistic degradation. Our findings provide quantitative confirmation of existing conjectures about core structure in the mental lexicon and the importance of integrating multi-relational word-word interactions in psycholinguistic frameworks.