The Mystery of Partner ‘Convergence’

Psychologists occasionally talk about the “Michelangelo phenomenon”: Over time, romantic partners start to slowly change each other, like sculptors chipping away at blocks of marble. Could I help you find a therapist? one might ask their beloved. What if we started jogging together? Hmm, wearing the fedora again? Eventually—the hope goes—they'll have chiseled a masterpiece of a companion. The result isn’t always a perfect David, but the point is that relationships mold people. And some researchers have found that when that happens, the art tends to look conspicuously like the artist.

They call this convergence—when partners grow more and more alike. Research suggests that couples can begin to resemble each other in personality, well-being, emotional responses, and health. One study followed couples, who had been together for an average of nearly four decades, over the course of eight years; partners matched each other’s baselines in traits such as openness, agreeableness, and neuroticism, and their fluctuations in those traits were synchronized too. Other studies have found that couples start sharing smell and taste preferences, hormone levels, and cortisol responses. This influence isn’t always for the better, either. Another study, brutally titled “Don’t Drag Me Down,” found that the happier participant in a pair tended to get significantly less happy.

But researchers don’t agree on what’s behind those findings. And some have started to question: Do partners actually keep growing toward each other, or do they just think they do? The latter, as it turns out, might ultimately be more important.

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Convergence could be driven by a few different things. One camp of researchers thinks that it can largely be explained by selection, the finding that we tend to date people we’re similar to in the first place. Partners commonly come from comparable backgrounds and cultures, are of similar ages, and have watched the same TV shows, Matthew Hammond, a psychologist at Victoria University of Wellington, in New Zealand, told me. If they already have a lot in common, it makes sense that couples might keep changing in similar ways over time.

Another camp, though, thinks that convergence goes beyond selection, to socialization—meaning that partners mold each other to be more like themselves. That could entail indirect influence. Partners share a life, engaging in many of the same activities and talking to many of the same people. But it can also include more direct sway—say, encouraging or discouraging certain behaviors, or steering conversations towards certain topics. (That tendency is sometimes given a name more intimidating than the “Michelangelo phenomenon,” social-control theory, which is exactly what it sounds like.) Take the “Don’t Drag Me Down” study. A less happy partner might, say, have fewer friends, Olga Stavrova, a co-author and psychologist at Tilburg University, in the Netherlands, told me. Perhaps that lack of support outside the relationship could leave the happier partner with more emotional responsibility, or the unhappier one’s sense of negativity might pervade the pair’s day-to-day interactions.

The socialization theory has its critics too. As part of a major convergence study, Hammond and his co-author expected to find that partners became more similar across a variety of well-being, attitude, and trait measures. But after surveying nearly 200 couples, they didn’t find much convergence at all. Partners did change over time—but independently of each other. One reason, Hammond told me, could be that many of these couples had been together for a long time—an average of about 27 years. Whether relationship length is driving that result is unclear, since some studies of more established couples have found convergence, but he wonders if that merging may just be something that helps partners connect early on.“You meet someone new; you fall in love. That’s when you change your personality and your belief systems,” he explained. “You try and fit together, and then, after a couple of years, you go … We’ve done enough merging that we can feel secure and similar to each other, and now we’re just going to do our own thing.”       

Over time, partners probably still imagine that they’re becoming more alike, even if it’s not true. In happy relationships, partners tend to have unrealistically positive ideas about each other, Hammond told me. If you’ve become more and more concerned about animal welfare, for example, you might assume that your partner has deepened those same beliefs. The reality might be a little different, and acknowledging it could introduce conflict. Or, even worse, it might make you think: If we aren’t exactly in lockstep, perhaps this isn’t the right person for me. That possibility is probably easier to ignore after years of being together.

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But convergence isn’t a necessary driver of a good relationship; if anything, it’s a symptom of one, William Chopik, a Michigan State University psychologist, told me. If you feel like you and your partner are seeing the world through the same lens, it might just mean you feel close to them. But you don’t need to be similar to your partner in every way, nor should you necessarily want to be; if one partner gets panicky in stressful situations, it’s helpful for the other to remain calm. If one partner tends toward insecure attachment, research suggests that a more secure partner can do wonders to build their trust. And, indeed, studies have found that when partners think they’re similar, that’s much more predictive of their attraction, perceived responsiveness to each other, and self-reported feelings of love than the degree to which they really are similar.

That’s not to say that partners should ignore any differences between them. Whether convergence is a reality, a projection, or a little bit of both—which researchers told me is likely—the takeaway is largely the same: What’s important is that they feel connected and understood, and it’s possible to maintain that unity while still acknowledging each other’s particularities. If partners see each other honestly, they can be more intentional about what parts of each other to whittle when they’re crafting their magnum opus. The people we love have immense power to change us—and however daunting that sounds, it’s a good thing.