Tracking the Integration of Novel Words into the Mental Lexicon: Evidence from Mouse Movement Trajectories

This study investigated lexical competition effects in novel word learning using mouse tracking methodology. We conducted two experiments examining how and when novel word representations become lexicalised, focusing on their ability to engage in competition with existing lexical entries. In Experiment 1, we used mouse tracking to conceptually replicate Weighall et al.’s (2017) eye tracking study, examining lexical competition between newly learnt word–referent pairs and familiar words both immediately after learning and following overnight consolidation. Mixed-effects analyses demonstrated immediate lexical competition effects for novel words. Competition did not differ significantly between words learnt on the previous day and those learnt on the day of testing. Experiment 2 demonstrated that displaying the referent associated with a newly learnt phonological competitor increased immediate lexical competition, even when targets in both conditions had trained phonological neighbours. The temporal dynamics of mouse trajectories revealed that familiar words produced earlier and larger peak competition effects compared to newly learnt words. These findings support models of word learning that allow for rapid lexical integration, while acknowledging that newly formed lexical representations may not immediately exhibit the same processing characteristics as well‑established words.