A Scientist’s Response To “We Needed Research To Tell Us This?”

September 18, 2015 by Justin Lehmiller


As someone who spends a fair amount of time engaging the public with the latest scientific research on sexuality and relationships, it is not uncommon for me to receive comments or tweets that say something to the extent of: “We needed research to tell us this?” The implication is that there really wasn’t a need for a given study to be conducted because we could have used “common sense” instead to figure out the results.

Completely dismissing research in favor of common sense is a bit of pet peeve for me. In fact, it ranks right up there with people asking me whether I can read their minds when they find out that I hold a degree in psychology. No, I’m not a psychic—that’s something completely different. But I digress.

I’ve received the “that’s just common sense” rebuttals frequently enough that I thought it made sense to write an article tackling them head-on with the goal of explaining why I think it’s problematic to dismiss research in this way. So, here goes.

The problem with people’s “common sense” beliefs about sex and relationships is that these beliefs reflect nothing more than the way that we as individuals try to make sense of the world based upon our personal experiences. Thus, common sense isn’t necessarily common because it’s based on nothing more than your own idiosyncratic lived experiences.

Because people can have very different lived experiences, different people can come to hold very different sets of “common sense” beliefs. As a result, when we take all of these beliefs and put them together, it’s not uncommon to find that they don’t make much sense at all and generate a lot of confusion. Let me give you an example.

Have you ever heard the saying “birds of a feather flock together?” I would venture to guess that many of you have and, further, that many of you also believe it to be true based on your own relationship experiences. In other words, many people think it’s just common sense that people tend to be attracted to partners with whom they share some degree of similarity and that similar partners tend to have happier relationships

But at the same time, have you ever heard the saying “opposite attract?” This is a pretty widely shared belief as well, and there are many folks out there who would argue that it’s just common sense that people tend to be drawn to partners who are different and that relationships work best when the partners complement each other.

As you can see, if we leave our understanding of relationships up to common sense, the results are quite inconsistent. Do we prefer partners who are similar to us or partners who are different?

This is where scientific research comes into play—it can help us to understand which beliefs about the world are correct or incorrect. Sometimes the results will be consistent with your “common sense,” but other times they won’t be.

I would encourage you to avoid dismissing all research that confirms your pre-existing “common sense” beliefs because it serves to feed into a broader expectation that science needs to be surprising or counterintuitive in order to be worthwhile. As I’ve written before, it is problematic to use level of surprise as the primary criterion by which we judge the value of science. Science doesn’t have to be surprising in order to tell us something important and useful.

With that said, perhaps you’re wondering what the scientific verdict is on “birds of a feather” vs. “opposites attract.” It turns out that there isn’t a simple answer and that, on some level, both sayings are correct. For instance, in a 2007 study published in the Journal of Social and Personal Relationships, researchers concluded that the most successful relationships were those characterized by similarity on some dimensions, but complementarity on others [1]. Specifically, in the words of the authors:

Romantic couples who reported the highest levels of relationship quality were more similar in terms of warmth but were more dissimilar in terms of dominance than romantic couples who reported the lowest levels of relationship quality.”

Thus, both “birds of a feather” and “opposite attract” are overly broad generalizations, with neither one telling us the full story. Whether similarity or complementarity is desirable and beneficial depends upon what specific personal traits or attributes you’re talking about.

It is only through research that we can come to generate nuanced understandings like this of what it is that makes our romantic and sexual relationships work. However, if we insist that scientists stop studying things that might seem intuitive or like “common sense,” we run the risk of never discovering the fascinating complexities about how the world works and what makes us tick.

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[1] Markey, P. M., & Markey, C. N. (2007). Romantic ideals, romantic obtainment, and relationship experiences: The complementarity of interpersonal traits among romantic partners. Journal of Social and Personal Relationships, 24(4), 517-533.

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Written by
Dr. Justin Lehmiller
Founder & Owner of Sex and Psychology

Dr. Justin Lehmiller is a social psychologist and Research Fellow at The Kinsey Institute. He runs the Sex and Psychology blog and podcast and is author of the popular book Tell Me What You Want. Dr. Lehmiller is an award-winning educator, and a prolific researcher who has published more than 50 academic works.

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