A new study shows that when it comes to friendship, it’s quantity over quality that matters in your 20s—and vice versa in your 30s.

That pattern turns out to be a predictor of psychological well-being later in life, and it happens to be one that comes relatively naturally to many of us.

“Earlier on in life, we’re more interested in exploring and acquiring as much information and knowledge about the world as we can. We do that in part by socializing with an array of people,” says Paul Duberstein, a psychiatry professor at the University of Rochester in New York. “As we reorient our goals and move into our 30s, we begin to clip the wings of our social network. The amount of people and the effort we spend on people in the network are more concentrated and of higher quality.”

The effects of this shift are documented in a study co-authored by Duberstein and published in Psychology and Aging in March. The study spanned 30 years and followed about 100 University of Rochester students from the 1970s.

At 20 and 30, the participants were asked to record their daily interactions with others, and to score them on intimacy and unpleasantness. Decades later, the subjects answered questions about their psychological well-being, including loneliness and depression, and the quality of their friendships. The researchers found that the quantity of friends at 20 predicted well-being in midlife, while at age 30 it was quality that was a better predictor.

In fact the study showed that having a higher quantity of friends at 30 did not predict later well-being, that “more frequent social activity at age 30 was associated with marginally worse psychological outcomes at age 50.” The authors suggest that having too many friends at 30 could actually prevent you from developing meaningful relationships. On the flip side, just meeting more people in your 20s, regardless of the depth of your interactions, has its own merits.

As the researchers admit, the sample size in this study was limited—the data was collected from educated, mostly white people who were privileged enough to attend an American university in the 1970s. But Duberstein predicts a wider and more diverse study would produce similar results.

There’s another wrinkle for social scientists to consider, though. As study co-author Cheryl Carmichael, assistant professor
of psychology at Brooklyn College, City University of New York, tells Quartz, the recently published research focused on face-to-face interactions, and was largely conducted before the explosion of social interactions we conduct every day using the electronic devices we carry around in our pockets.

Soon, with better data collection and more ways to socialize, we can expect a more nuanced look at how our friendships affect us later in life, she and Duberstein predict.

Image by Ippei Suzuki on Flickr, licensed under CC-BY-2.0.