Lexical–semantic networks in a native and a foreign language: a network science analysis of Spanish (L1) and German (L3) based on written verbal fluency tasks

This study examines lexical–semantic network organisation in multilingual learners by comparing verbal fluency in a fully consolidated first language (Spanish) and a less consolidated foreign language (German), acquired as a third language. Thirty-four university students completed semantic, phonological, and verb written fluency tasks. Network science metrics assessed word output, lexical diversity, and topological properties including clustering, modularity, small-world characteristics, and core–periphery structure. Results revealed significantly higher written verbal fluency in the native language across all tasks, with greater word production and lexical diversity. Native-language networks displayed stronger structural properties, including higher modularity and denser core integration, reflecting a more efficient, hierarchically organised lexicon. Conversely, foreign language networks exhibited fragmentation and reliance on a limited set of high-frequency items, consistent with less consolidated lexical organisation. Semantic fluency tasks produced more cohesive networks, whereas phonological tasks showed greater variability, particularly in the foreign language. Verb networks demonstrated strong cohesion in both languages, highlighting the influence of communicative relevance. These findings support spreading activation and prototype-based accounts of lexical organisation and demonstrate that key network properties, such as small-world and core–periphery patterns, emerge even in developing foreign language systems.