New research from the University of Warwick and the University of Salzburg found that children don’t understand competitive behavior until age 4. Before that children did not understand that people could have conflicting motivations.

The researchers asked children ages 3 to 5 to engage in a game involving beads. Children could take the beads from a neutral location or from each other’s pot. Many children did not take from each other, even when beads were taken from them. The change in behavior occurred for most children around age 4. That is when most tended to behave more competitively.