From Marshmallows to Rationality

Perhaps most people have already heard of the famous Marshmallow study. In this study, the young participants were offered a big fluffy marshmallow and a choice: they can either pop one in their mouths right away or get two if they could hold onto it for a few minutes. Imagine going back in your 4-year-old self, what would you choose? Let’s take a look at what the kids did in this experiment.  

Now the question is: Which is the more rational decision? Eating the marshmallow right away? Or to waiting longer to get an extra treat?

The general belief is that the kids who walked away with two marshmallows won the game. According to the classical rationality model, we should compare the situations and choose the one that can maximize the gain. In this case, having two marshmallows is better off than just getting one. In addition, for those who didn’t eat immediately, they sacrificed the immediate satisfaction of enjoying the marshmallow for a better outcome in the long run. So this is consistent with the evolutionary viewpoint as well.

We are not as rational

However, much evidence shows that humans are not purely rational being. One reason is that we are not as capable of sticking with rational decisions as we think. In the video, it was entertaining to see how children struggled to pull themselves back from the enticing marshmallow. As we can tell, it takes a lot of willpower, which is essentially the direct attention in our brain, to control our behaviors. But attentional resources are scarce. What happens when we run out of them? We get exhausted, impatient, we give up and grab the marshmallow. Maybe it is not that children who ate the first don’t want the second one, but it is just so hard to turn down the temptation. Or they happened to be just really hungry at that time, which makes it even harder. In addition, when the experimenter stressed how good it tastes, it took children less time before reaching out their hands. It is just like the tactic of salespersons, which is to make things so wonderful that you feel the urge to buy them even though you don’t really have the needs. Those distractions amplify the irrational impulse, consume more direct attention and keep us from making rational decisions.

(Images from Tim Urban’s blog, Wait But Why)

Cognitions shape our views
Another thing is that our existing cognitive maps influence our thinking. In 2013, researchers at the University of Rochester did an extended version of this study with a controlled factor. Before having the marshmallow task, children were asked to do something similar: they could paint with what they have already, or wait for longer to get better tools. However, in some cases, the experimenter returned with the tools but not in others. Would the kids be more likely to eat the first marshmallow if they had reason to doubt the researcher’s promise to come back with a second one? Suppose that we are perfectly rational, what will we do? We should wait regardless of the first scenario. Why? Well, as we do not know any other information to predict the situation, the chance of the experimenter coming back with reward has not changed which is 50/50. Based on the rule of Expectancy-Value, waiting for the second marshmallow still outscores the other.

Expectancy	Value	E*V
.5	1	=.5
.5	2	=1 ⭐

Turns out, the result was the opposite. Children who had an empty-handed experimenter in the first scenario tend to eat the first marshmallow whereas those who had a positive one did the contrary. Clearly, the classical rational rule isn’t the way it works here. If children think that the experimenter is unreliable and the chance of getting the reward is slim, they might want to eat it right away rather than risking to wait for nothing again. This suggests that we evaluate things based on our cognition of the environment and past experience.

Humans are also driven by heuristics. By manipulating the environmental condition, researchers showed that things happened recently can influence our decision making. We adjust behaviors so as to better adapt to new changes. As for emotions, besides the sense of trust, other factors like the fear for rivals could also be a factor. For example, kids who grow up with a lot of siblings might tend to eat it faster because waiting too long could mean the increased chance of being taken away by others, especially when things are not enough to share.

Going back to the question at the beginning, what is the better thing to do? There is not a single metric for judging all the decisions. While it is important to consider things under different context, what really makes a difference is whether the choice serves the ultimate goal – that is to help human better adapt and survive in the complicated environment.

References:

 1. Kidd, Celeste. “Rational snacking: Young children’s decision-making on the marshmallow task is moderated by beliefs about environmental reliability”, Cognition. 2013 Jan; 126(1): 109–114.

2. Michael Bourne, “We Didn’t Eat the Marshmallow. The Marshmallow Ate Us”, New York Times. http://www.nytimes.com/2014/01/12/magazine/we-didnt-eat-the-marshmallow-the-marshmallow-ate-us.html?_r=0