Fine Motor Skills and Later Vocabulary Development Before and During the COVID-19 Pandemic: Evidence from Japanese Childcare Settings

Background/Objective: Early fine motor skills are consistently associated with later language development, but it remains unclear as to whether this relationship is maintained among children showing early development during the COVID-19 pandemic. In this study, we investigated whether the longitudinal association between early fine motor skills and subsequent vocabulary development differed between children demonstrating early development before and during the COVID-19 pandemic. Method: The participants were 1150 children (pre-pandemic cohort: n = 703; pandemic cohort: n = 447) attending licensed childcare centers in Japan. Hierarchical multiple regression and moderation analyses were conducted to examine whether fine motor skills at Time 1 (T1) predicted vocabulary at Time 2 (T2) after adjusting for baseline vocabulary, demographic characteristics, and home-rearing environment. Results: Fine motor skills at T1 significantly predicted vocabulary at T2 in both cohorts. A significant interaction between cohort and fine motor skills was observed (B = −0.09, p = 0.041), indicating that the strength of this association differed between the pre-pandemic and pandemic cohorts. Children in the latter demonstrated lower vocabulary outcomes across most levels of fine motor proficiency, with cohort differences becoming more pronounced with higher levels of baseline fine motor skills. Conclusions: The findings suggest that the fundamental association between fine motor skills and vocabulary development remained evident despite pandemic-related restrictions; however, changes in children’s social and communicative environments may have reduced opportunities to translate motor competencies into linguistic gains. These results highlight the importance of supportive social interactions and communicative experiences in facilitating early developmental processes.