One book, two minds: Understanding differences in maternal mental state talk during storytelling across siblings

When calibrated to a child’s developmental readiness, maternal mental state talk (MST) presents a powerful mechanism through which mothers can scaffold their children’s understanding of the mind. This study investigated developmentally sensitive differentiation in maternal MST during dyadic interactions across two siblings aged 2.5 to 8 years. Using a within-family design, mothers were observed engaging separately with each child using a wordless picture book, allowing for direct comparison of maternal talk across siblings. Mothers demonstrated less verbosity, proportionally fewer perception terms and proportionally more cognition terms during interactions with older compared to younger siblings. Moreover, maternal adjustment in cognition term use across siblings was associated with developmental differences in theory of mind understanding, but not age, language, or IQ, suggesting maternal linguistic sensitivity to each child’s unique social-cognitive capabilities. This study highlights how maternal MST is dynamically shaped by the real-time needs and capacities of each child in the family system.