Children's thinking about their own and others' regret and relief.

In two experiments using a decision-making game, we investigated children's thinking about regret and relief. In Experiment 1 (N=43, 31 children [5 years 4 months to 8 years 2 months of age] and 12 adults), participants chose between two boxes containing different numbers of stickers. They rated their happiness before learning that the other box contained more (regret) or fewer (relief) stickers. They rerated their chosen box with the counterfactual knowledge. The experience of regret was evident at 5 years of age, and the experience of relief was evident at 7 years of age. In Experiment 2 (N=69, 53 children [5 years 3 months to 6 years 11 months of age] and 16 adults), participants either played the game (self condition) or watched another play the game (other condition). Children in the self condition confirmed the results from Experiment 1. We found no evidence that children up to 7 years of age were able to predict others' regret and relief, a finding that suggests differing developmental trajectories between experiencing and understanding others' regret and relief.