In these cases, children who eat the one marshmallow in front of them rather than waiting for two later are actually making the right choice, given the environmental constraints they typically face. One study, for instance, found that when children were given the option to have one treat now or two treats later by either experimenters who had previously kept their promises or those who had not, they sensibly scarfed down the first sweet if their prior experience was that the researcher was flaky.
