Toddlers’ causal interventions reveal a grasp of the temporal priority principle
This study investigated whether one- and two-year-olds (N=133, 72 female, Western) grasp that causes must precede their effects (the temporal priority principle). Toddlers watched an adult perform action A on a puzzle-box, following which a sticker dispensed (effect E); following which action B was performed. In line with the temporal priority principle, toddlers were significantly more likely to manipulate A than B (Experiment 1), even when A was spatially disconnected from the sticker dispenser and further from it than action B (Experiment 2). Experiment 3 ruled out that toddlers acted based on a primacy effect in Experiments 1—2. A lack of evidence for any age effects suggests children grasp temporal priority from the second year of life.