Psychology is hard

A case of the test not being wrong, but unknowingly incomplete and therefore with misleading conclusions. Which is often how science works. That's not a flaw of the method, it's an inevitable part of learning.

The researchers next added a series of “control variables” using regression analysis. These controls included measures of the child’s socioeconomic status, intelligence, personality, and behaviour problems. As more and more factors were controlled for, the association between marshmallow waiting and academic achievement as a teenager became insignificant. Calarco concluded that the marshmallow test was not about self-control after all, but instead it reflected affluence. Children from lower-class homes had more difficulty resisting the treats than affluent kids, so it was affluence that really influenced achievement.

If researchers were unreliable in their promise to return with two marshmallows, anyone would soon learn to seize the moment and eat the treat. He illustrated this with an example of lower-class black residents in Trinidad who fared poorly on the test when it was administered by white people, who had a history of breaking their promises. Following this logic, multiple studies over the years have confirmed that people living in poverty or who experience chaotic futures tend to prefer the sure thing now over waiting for a larger reward that might never come.

Those theories—and piles of data—suggest that poverty makes people focus on the short term because when resources are scarce and the future is uncertain, focusing on present needs is the smart thing to do. However, when chronic poverty leads to a daily focus on the present, it undermines long term goals like education, savings, and investment, making poverty worse.

While it may be tempting to think that achievement is due to either socioeconomic status or self-control, we have known for some time that it’s more complicated than that. Early research with the marshmallow test helped pave the way for later theories about how poverty undermines self-control. We should resist the urge to confuse progress for failure.

https://behavioralscientist.org/try-to-resist-misinterpreting-the-marshmallow-test/