Toddlers can learn cause-effect relationships between single actions and outcomes. However, real-world causality is often more complex. We investigated whether toddlers (12- to 35-month-olds) can learn that a sequence of two actions is causally necessary, from observing the actions of an adult demonstrator. In Experiment 1, toddlers saw evidence that performing a two-action sequence (AB) on a puzzle-box was necessary to produce a sticker, and evidence that B alone was not sufficient. Toddlers were then given the opportunity to interact with the box and retrieve up to five stickers. Toddlers had difficulty reproducing the required two-action sequence, with the ability to do so improving with age. In Experiment 2, toddlers saw evidence that performing a single action (B) was sufficient to produce an effect (i.e., a sequence was not causally necessary). Toddlers were more successful and performed fewer sequences in Experiment 2, suggesting some sensitivity to the sequential causal structure.

Toddlers, like older children and adults, can learn cause-effect relationships between a single action and its outcome.However, causality in the real-world is more complex. We investigate whether toddlers can learn, from observing an adultsdemonstration, that a sequence of two actions is causally necessary for producing an effect. In Experiment 1, toddlers andpreschoolers (N=142; ongoing) saw evidence that a 2-action sequence was necessary to make a puzzle-box dispense asticker, before trying to get stickers themselves. Preliminary results indicate that older children produce more sequencesthan younger children. Experiment 2 (N=42; ongoing) is examining whether 1- and 2-year-olds behave differently from inExperiment 1 when the demonstration provides evidence that a sequence of actions is not necessary (specifically, that thesecond action alone is causally effective). Although preliminary, our findings suggest that the ability to accurately infercausal structure from action sequence demonstrations may develop over early childhood.