In another experiment, a group of children was made to steal stickers from the other group. Later on, the roles were reversed, and the children from the first group were given the opportunity to steal the others’ stickers. Consequently, the majority of the first group retaliated and stole stickers from the person who had taken it from them in the first task.
So, even though children can clearly and equally remember the people who were “good” and “bad” to them, they were only eager to return the negative behavior to the other person.
This implies that gratitude should be taught to children in the form of short fables or direct examples about people returning favors and acknowledging positive gesturers directed towards them.
For example, in a final experiment, when children where told a story about a player who returned a sticker to another player who had done them a favor in a previous round. A significant number of children did indeed show gratitude and direct reciprocity, implying that it is a principle that should be learned and then applied.
Chernyak, N., Leimgruber, K. L., Dunham, Y. C., Hu, J., & Blake, P. R. (2019). Paying back people who harmed us but not people who helped us: Direct negative reciprocity precedes direct positive reciprocity in early development. Psychological science, 30(9), 1273-1286.