Toddlers' symbolic play in dyadic mother-child and triadic mother-child-older-sibling interactions.

Symbolic play supports crucial aspects of early childhood development, including language and social-cognitive skills. Parent-child dyadic play has been shown to facilitate symbolic play development, but less is known about the addition of siblings (triadic interactions), which may present both opportunities and challenges. We examined toddlers' symbolic play across dyadic (mother-child) and triadic (mother-child-sibling) free-play interactions recorded through videoconferencing. Twenty toddlers (aged 1.5-2.5 years, eight girls) were observed playing with their mothers and older siblings (aged 3.5-7.5 years, ten sisters) in two standardized 10-minute play sessions at their homes. We coded the frequency, duration, variety, toddler initiative, and complexity of symbolic play. Consistent with our hypothesis, toddlers demonstrated significantly higher levels of symbolic play in dyadic versus triadic interactions overall (p < 0.0001, Cohen's d = 0.953) and across all measured dimensions (p < 0.05 to p < 0.001, Cohen's d = 0.637-0.915). This suggests that dyadic play may optimize conditions for symbolic play development, and/or that the addition of siblings introduces competing demands that reduce opportunities for advanced symbolic play. The results have implications for understanding how family configuration influences early play experiences and may inform the design of interventions to support symbolic play development in different social contexts.