Easy or difficult? Children's understanding of how supply and demand affect goal completion.

Three experiments examined children's understanding of how supply and demand affect the difficulty of completing goals. Participants were 368 predominantly White Canadians (52% female, 48% male) tested in 2017-2022. In Experiment 1, 3-year-olds recognized that obtaining resources is easier where supply exceeds demand than where demand exceeds supply. However, in Experiment 2, 3-year-olds were insensitive to supply and demand when comparing situations where demand exceeded supply to a greater or lesser degree. Finally, Experiment 3 revealed a developmental lag in 3- to 7-year-olds' understanding of how supply and demand affects goal completion: Children succeeded when contrasting a surplus and a shortage of supply relative to demand at 4;2. But they only succeeded when contrasting degrees of greater supply than demand at 5;10.