Rational snacking: Young children’s decision-making on the marshmallow task is moderated by beliefs about environmental reliability

Children are notoriously bad at delaying gratification to achieve later, greater rewards (e.g., Piaget, 1970)—and some are worse at waiting than others. Individual differences in the ability-to-wait have been attributed to self-control, in part because of evidence that long-delayers are more successful in later life (e.g., Shoda, Mischel, & Peake, 1990). Here we provide evidence that, in addition to self-control, children’s wait-times are modulated by an implicit, rational decision-making process that considers environmental reliability. We tested children (M = 4;6, N = 28) using a classic paradigm—the marshmallow task (Mischel, 1974)—in an environment demonstrated to be either unreliable or reliable. Children in the reliable condition waited significantly longer than those in the unreliable condition (p < 0.0005), suggesting that children’s wait-times reflected reasoned beliefs about whether waiting would ultimately pay off. Thus, wait-times on sustained delay-of-gratification tasks (e.g., the marshmallow task) may not only reflect differences in self-control abilities, but also beliefs about the stability of the world.