If #children are paired in a marshmallow test and one promises not to eat their treat, the other is much more likely to also refrain from eating it.
Any parent could tell you that children of this age are really big on the importance of promises, and science largely concurs; a promise has been shown to enhance interdependent cooperation in this age group.
Younger children were slightly more likely to succeed.
https://arstechnica.com/science/2025/05/a-peers-promise-can-help-kids-pass-the-marshmallow-test/
