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The Major Problem With Research on Intimate Relationships

This major issue persists across other areas of the human experience.

Key points

  • New research exposes a major problem with the scientific study of intimate relationships.
  • This major issue persists across relationships research as well as other areas of the human experience.
  • Human behavior varies along with factors such as gender identity, age, ethnic background, and sexual orientation.
Jonathan Borba/Unsplash
Source: Jonathan Borba/Unsplash

In a new article, published in the Journal of Social and Personal Relationships, lead author Hannah Williamson and colleagues from the University of Texas at Austin expose a major problem with the scientific study of intimate relationships: a large majority of the research in this area does not reflect the characteristics of the population in some very important ways.

The Problem of Underrepresentation

This major issue of underrepresentation is not unique to the study of relationships. In this area as well as other areas of human experience, “despite repeated calls throughout the years to increase the diversity and inclusion of underrepresented groups in our samples, the majority of our knowledge about human behavior continues to be drawn from a limited portion of the human population.” This problem is so important because so much of human behavior varies along with factors such as gender identity, age, nationality, ethnic background, religion, and sexual orientation. For example, as the authors recount, although “romantic relationships are a nearly universal phenomenon, with the vast majority of people around the world engaging in them … there are large differences in the extent to which people engage in specific relationship behaviors such as marriage, cohabitation, divorce, and non-marital childbearing.” Because the nature of our intimate relationships changes along with our diverse backgrounds, it is critically important for relationship researchers to recruit diverse and underrepresented samples in order to more fully investigate intimate relationships.

The Current Research

In the current research, the authors assessed “the extent to which research on intimate relationships has been inclusive of individuals and couples from backgrounds traditionally underrepresented in social and behavioral science.” The researchers began reviewing the intimate relationships literature in early 2019 and they examined research published between 2014 and 2018. The authors included publications from five top journals including the Journal of Family Psychology, the Journal of Marriage and Family, the Journal of Personality and Social Psychology, Journal of Social and Personal Relationships, and Personal Relationships. In order to be included in the current meta-analysis, the research papers had to include an empirical study assessing “relationship processes and outcomes” with a relationship-related dependent variable (such as relationship satisfaction or communication). The authors identified 771 unique studies to include in their analyses. These studies were coded for factors such as the type of sample (e.g., undergraduate students, nationally representative sample), average age, ethnic background, country, educational status, income, sexual orientation, and gender identity.

The Findings

The researchers found that the vast majority of studies published in these top journals were conducted within the U.S. (73%) while most of the other studies were conducted in other English-speaking countries such as the U.K., Canada, and Australia. Only a small proportion of studies were conducted in Europe (10%) and very few were conducted in Asia, Israel, Latin America, Africa, or the Middle East. While most of the samples were community-based samples (57%), a large number of studies included only undergraduate students (27%). Eleven percent of studies included samples gathered via the internet while only 6% of studies included nationally representative samples. Furthermore, although intimate relationships are inherently dyadic in nature, most studies used individual data (58%) rather than data from both members of a couple.

With regard to age, the average age of participants in these research projects was 30 years old. Most studies included participants with an average age in their 20s (43%) followed by 30s (24%) and teens (17%). Only 16% of studies were drawn from samples with an average age of 40 or older. According to the authors, adults aged 40 and older make up almost half of the U.S. population, therefore older adults are widely understudied in intimate relationships research. The authors also found that most research was conducted with participants who had some college or a higher educational attainment level (84%), showing an overrepresentation of highly educated individuals in intimate relationships research. Similarly, most research was conducted with middle-class samples (64%), and therefore individuals with lower socioeconomic status are underrepresented.

Surprisingly, 34% of the studies the authors analyzed did not include information about the racial or ethnic background of their participants. Of those studies reporting ethnic information, 68% of those samples were primarily white, while only 21% were ethnically diverse and only 11% included a sample that was primarily made up of people of color. As the authors state, “White individuals are being oversampled in comparison to their population prevalence and all other races and ethnicities are being underrepresented.” The authors also found that, compared to their prevalence in the U.S., inter-racial couples were also understudied. Furthermore, a large proportion of studies (32%) did not indicate the sexual orientation of the participants. Of those studies which reported sexual orientation, only 4% of studies focused on same-sex couples and only 12% of studies included any same-sex couples. Only three studies included relationships in which at least one partner was transgender.

The Conclusions

These recent findings suggest that “despite early warnings about the homogenous demographic makeup of samples in relationship science … the field does not seem to have corrected course.” The authors state that many groups such as “people with low socioeconomic status, older adults, and inter-racial couples are underrepresented in the relationship science literature compared to their prevalence in the population.” Additionally, although “sexual and gender minorities are represented in the relationship science literature proportional to their population prevalence … proportional representation in the literature may not be sufficient to build a robust understanding of this (and other minority) groups” due to differences within these groups. The authors conclude that there is a “widespread lack of diversity and inclusion of underrepresented groups” in intimate relationships research. This lack of inclusion is “a threat to the credibility and validity of relationship science because we currently do not know whether the vast majority of our theories and findings generalize beyond a small portion of the human population, and we do not understand the unique relationship processes occurring in non-majority groups.” The authors recommend that we “increase the extent to which underrepresented groups are included in relationship science research, and to do so in a manner that is respectful of, and relevant to, these communities.”


Williamson, H. C., Bornstein, J. X., Cantu, V., Ciftci, O., Farnish, K. A., & Schouweiler, M. T. (2021). How diverse are the samples used to study intimate relationships? A systematic review. Journal of Social and Personal Relationships, doi:10.1177/02654075211053849