“Romantic compatibility theory”—it has a nice ring, doesn’t it? This theory suggests that relationship success is a function of the unique combination of two individuals’ qualities. He appreciates her art, they both love cycling, and her positivity keeps him motivated when he needs a boost. Obviously, such similarities and connections between partners impact romantic outcomes—right?
Online dating sites certainly think so, and many enthusiastically advertise “matching algorithms” that will connect you with uniquely suited dates. Their secret formulas take demographics into account, but they claim that their matching process goes far deeper, mining the stuff of personality traits and values to deliver lasting love.
These algorithms assume the seeds of compatibility can be determined before the first date, and that compatibility powerfully impacts relationship success. But does existing research support these assumptions? A surprising new analysis of online dating suggests probably not.1
To place the argument in context, consider the fact that researchers who want to understand and predict romantic outcomes usually study variables from one of three camps:
- Quality of Interaction
- Individual characteristics
Which of these raw materials can be fed into matching algorithms? Quality of interaction is the strongest predictor of relationship success. But because online matching inherently involves new partners, interaction quality is not available to help make matches. The algorithm could factor in circumstances (e.g. a “chronic stressors” score), but few dating site questionnaires ask about them. Consequently, matching algorithms are left only with individual characteristics to tip the hand of long-term happiness. In practice, most matching sites (such as eHarmony) introduce couples who share similar individual characteristics.
Is this really enough? Consider the results of an impressive recent study evaluating the link between individuals’ personalities and their relationship satisfaction. Based on analyses from nationally representative samples in Australia, the United Kingdom, and Germany2, researchers concluded that “each partner’s personality accounted for approximately 6% of the variance in his or her own relationship satisfaction, and 1-3% of the variance in the other partner’s relationship satisfaction…the similarity between partners’ personalities accounted for an additional 0.5% of the variance in romantic outcomes.” So…23,000 people from three countries say matching algorithms might predict a whopping 0.5% of future relational satisfaction, leaving other factors to predict the remaining 99.5%.
It gets worse. A meta-analysis of 313 studies found that “the effect of actual similarity on satisfaction in existing relationships was not significantly different from zero.”3 Yet another meta-analysis found that neuroticism (i.e., the proclivity to experience negative emotions), long-established as the personality trait with the most impact on relationship success, accounted for less than 5% of variance in relationship satisfaction over time.4 All in all, factors beyond the reach of matching algorithms likely account for over 95% of couples’ long-term relationship satisfaction.
Now, to be fair, these findings do not specify what power individual characteristics hold in the early stage of romantic attraction and relationship development—the stage online dating sites should care about most. Maybe these matching algorithms should stop pretending they can speak to long-term success and should focus instead on predicting a good first date.
1Finkel, E. J., Eastwick, P. W., Karney, B. R., Reis, H. T., & Sprecher, S. (2012). Online dating: A critical analysis from the perspective of psychological science. Psychological Science in the Public Interest, 13(1), 3–66.
2Dyrenforth, P. S., Kashy, D. A., Donnellan, M. B., & Lucas, R. E. (2010). Predicting relationship and life satisfaction from personality in nationally representative samples from three countries: The relative importance of actor, partner, and similarity effects. Journal of Personality and Social Psychology, 99, 690–702.
3Montoya, R. M., Horton, R. S., & Kirchner, J. (2008). Is actual similarity necessary for attraction? A meta-analysis of actual and perceived similarity. Journal of Social and Personal Relationships, 25, 889–922.
4Karney, B. R., & Bradbury, T. N. (1995). The longitudinal course of marital quality and stability: A review of theory, methods, and research. Psychological Bulletin, 118, 3–34.
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