Action anticipation based on an agent's epistemic state in toddlers and adults

Do toddlers and adults engage in spontaneous Theory of Mind? This multi-lab collaboration examined whether 18- to 27-month-olds’ and adults’ anticipatory looks distinguish between two basic forms of epistemic states: knowledge and ignorance. In adults (n = 703, 68% female), we found clear evidence that they do: they showed simple goal-based action anticipation in pilot studies and differentiated between knowledge and ignorance conditions in the main study. In toddlers (n = 521, 49% female), results were less conclusive. While demonstrating goal-based action anticipation in pilot studies, they did not differentiate between knowledge and ignorance as predicted. Future research can explore adults’ sensitivity to more complex epistemic states like true/false beliefs and clarify whether toddlers’ results reflect competence or performance limitations.