Life is not simple. Doing one thing, or behaving in one specific way, will not mean you will be happier, healthier or richer than anyone else – there are too many confounding, interrelated factors to consider.

With that in mind, you’d be forgiven for being skeptical of a range of recent headlines that claim that “this one personality trait” will determine whether or not you will be wealthy in the future. So let’s take a look at what the study, and its authors, are actually saying here.

First, this is all about delayed gratification, an oft-researched topic in psychology. This involves delaying acceptance of an immediate, short-term reward in preference of a later, normally more meaningful prize. It has links to self-control and the nebulous concept of willpower, which has led to some to suggest those that can engage in it will do better off in later life.

Published in Frontiers in Psychology, the team from Temple University explain income varies according to things as intuitive as educational levels and as obscure as height. They also point out how it’s uncertain which factors are most important.

Using a large group of 2,546 people from a diverse range of age groups and demographics, the team deployed machine learning algorithms to look for relationships between income and a range of possible predictors. They found that, more than age, ethnicity, or height, “delay discounting” is more predictive of future income.

This is essentially delayed gratification, with smaller immediate rewards being eschewed for more profound later prizes. But wait! There's more.

The study actually stresses that other factors, like education, occupation and zip code, are all more important than delayed gratification. Most noteworthy, perhaps, is that males were consistently higher earners than females across the board, adding more to the pile of evidence regarding the pervasive gender wage gap.

Lead author Dr William Hampton, an expert in decision neuroscience from Temple University, explained in a recent interview that although delayed gratification seems a better predictor than age, height, and ethnicity, they “can’t say whether lower delay discounting leads to higher income or whether higher income leads to lower discounting.”

This is because the paper is a cross-sectional study, one that looks at data points at a specific point in time. It’s not a longitudinal study, which means that changes over time and cause-and-effect relationships cannot be determined. Instead, it’s an analysis of a snapshot, and correlation, infamously, does not necessarily mean causation, whichever direction it may be going in.

At the same time, the team also emphasizes that other research disagrees on whether or not delay discounting behavior remains stable or ever-changing throughout life. If it is a mutable, plastic variable, then how can one say it’s a predictor of future income?

Delayed gratification also isn’t the Holy Grail it was once thought to be.

One of the more famous studies investigated the phenomenon was the Stanford marshmallow test. You put a tasty treat in front of a child, and explain they can either eat that one or wait for 15 minutes to get twice as many.

Those that waited to get double the reward were said to have stronger willpower. Following the original children involved in the test through their lives, those who demonstrated the ability to delay gratification were associated with better test scores and improved career prospects.

A 2018 re-envisioning of the original 1960s Stanford study, involving 10 times the participants and including children from a wide range of demographics, found that willpower wasn’t what the test was probably measuring.

Instead, affluence appeared to be the strongest factor, with the kids from richer families finding delaying gratification easier. The experience of the richer kids suggested waiting would have no negative consequence; that of the poorer kids suggested delays would lead to missed opportunities, and that they should take any positives when they arrive for fear of losing them.

The point is that this 2018 paper arguably debunked the idea that delayed gratification is strongly indicative of greater outcomes – rather, it’s the person’s background that influences success in the long-run.

Pointing to pre-existing research, the Temple team speculate that an inability to engage in delay discounting signals propensity toward a range of negative behaviors, from drug abuse to pathological gambling. Perhaps, per the paper, it’s all connected to “undesirable life choices" that influence income levels.

At this point, however, there are too many question marks to make any sweeping statements about the vital nature of delayed gratification.