The Role of Mutations in Welsh Lexical Access

Abstract

This thesis investigates how initial consonant mutation (ICM) in Welsh affects spoken-word recognition and lexical access in Welsh-English bilinguals. Most psycholinguistic models assume stable word onsets, yet in Welsh, morphosyntactically triggered mutation alters the initial segment of many lexical items, presenting a typologically distinctive challenge to established frameworks. Four behavioural experiments were conducted. Experiment 1 (a sentence judgement task) confirmed that native first-language Welsh speakers possess robust grammatical expectations for canonical mutation, validating the assumptions underpinning the lexical access tasks that followed.

Experiments 2 and 3 employed two-alternative forced choice (2AFC) reaction-time tasks to examine lexical competition. In English (Experiment 2), both English monolinguals and Welsh-English bilinguals showed clear and statistically indistinguishable onset competition effects. In Welsh without mutation (Experiment 3), Welsh-English bilinguals again showed onset competition, but also, rhyme competition was of similar magnitude; a pattern not previously reported in clean listening conditions. Reaction times were also slower in Welsh than English, suggesting increased processing demands in the Welsh language context. Experiment 4 introduced overt soft mutation into the Welsh task. Although numerical slowdowns were observed for mutated and competing forms, no condition reached statistical significance, and the study was underpowered to detect small effects.

Overall, the findings suggest that while Welsh-English bilinguals may use similar lexical competition strategies across languages, the phonological and morphosyntactic properties of Welsh influence the weighting of onset versus offset cues. These findings carry implications for bilingual lexical architecture, the modelling of morphophonological variability, and testing the assumptions of recognition models such as TRACE and Shortlist B when applied to typologically diverse languages.

Date of Award	3 Dec 2025
Original language	English
Awarding Institution	Bangor University
Supervisor	Sarah Cooper (Supervisor) & Giulia Bovolenta (Supervisor)