Maturity gets used almost interchangeably with being smart, the mature person is often just imagined as the sharpest one in the room, the one who read the most and argues the best. Two studies that measured maturity directly, rather than assuming it tracks with intelligence, suggest that conflation is a mistake, and that something quite different is actually doing the work.
The clearest evidence comes from a 2013 study by Igor Grossmann, Jinkyung Na, Michael Varnum, Shinobu Kitayama, and Richard Nisbett, published in the Journal of Experimental Psychology: General. The researchers recruited a stratified random community sample of 241 adults spanning ages 25 to 90 and had them reason through real social-conflict scenarios, scoring their responses on dimensions drawn from wisdom research, taking multiple perspectives, tolerating compromise, and acknowledging uncertainty and change. This “wise reasoning” score, not raw intelligence, predicted meaningfully better outcomes: less negative affect, better relationship quality, less depressive rumination, and more positive language in everyday speech. Standard intelligence measures, tested alongside wise reasoning in the same sample, showed no significant relationship to well-being at all. The effect also helped explain why well-being tends to rise with age, an effect that was strongest specifically among middle-aged and older adults, tying psychological maturity to something distinct from simply accumulating birthdays.
A second study helps confirm that this kind of maturity isn’t just a wisdom-research artifact, it holds up as a genuinely separate trait from intelligence more broadly. In a 2004 meta-analysis by Lawrence Cohn and P. Michiel Westenberg, published in the Journal of Personality and Social Psychology, the researchers statistically combined 52 correlations from 42 separate studies, covering 5,648 participants, to test whether Jane Loevinger’s widely used measure of ego development, a well-established gauge of emotional and psychological maturity, was really just a stand-in for IQ. The correlations between ego level and intelligence came out small to moderate, ranging from .20 to .34 depending on the intelligence test used, clearly related but clearly not the same thing. More strikingly, across 16 studies that statistically controlled for intelligence, ego level still predicted real-world outcomes like aggressive or prosocial behavior in 94 percent of the tests conducted, meaning maturity was doing independent predictive work almost every time it was measured.
Together, these two studies point to maturity as a real, distinct psychological quality rather than a byproduct of intelligence. Grossmann and colleagues’ research shows that wise reasoning about real conflicts, not raw cognitive horsepower, is what tracks with genuine well-being and better relationships. Cohn and Westenberg’s research shows that emotional maturity holds up as its own predictor of real-world behavior even once intelligence is statistically removed from the picture, and does so with striking consistency across dozens of studies. Between the two, the art of maturity looks less like a byproduct of being clever and more like a separate, learnable way of engaging with other people and difficult situations.
It’s worth being honest about what these two studies don’t establish. Grossmann and colleagues’ research is correlational, and while the pattern held across a genuinely age-diverse sample, it can’t fully rule out that some other underlying factor contributes to both wise reasoning and well-being. Cohn and Westenberg’s meta-analysis draws from decades of studies using Loevinger’s specific measure of ego development, which is well-validated but represents one particular way of operationalizing maturity, other frameworks might tell a somewhat different story.
Within those honest limits, the research offers a genuinely useful correction to how maturity tends to get talked about. It isn’t a synonym for intelligence, and it doesn’t max out by a certain age. The evidence suggests it’s a specific, ongoing capacity, for weighing other perspectives, tolerating compromise, and regulating one’s own reactions, that keeps developing well into later life, regardless of how sharp someone was to begin with.