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Cultural Differences May Be Greater Than We Think

Published studies may underestimate the impact of culture on human psychology.

Key points

  • Most studies that investigate the impact of culture on human psychology are cross-national studies.
  • Country and culture are not synonymous. National groups are generally more diverse and more variable than cultural groups.
  • Effect sizes are slim when participant responses are highly variable. Published studies may underestimate the impact of culture on psychology.

By now, most Psychology Today readers are familiar with the overall picture, if not the finer details. People who grow up in different cultural contexts often think, feel, and behave differently.

Some of the differences are truly remarkable (White, 2020).

  • Africans who grow up in rural villages are much less susceptible to the Müller-Lyer illusion than Europeans who grow up in cities.
  • The prevalence of ADHD in the U.S. is 2 to 3 times higher than in Norway and Sweden.
  • Compared to German students, Chinese students can store about 20% more information in short-term memory.
  • People in Australia, Chile, Turkey, and the U.S. report much higher levels of self-esteem than people in Bangladesh, Hong Kong, Japan, and Taiwan.
Image by Heejin Jeong from Pixabay
Source: Image by Heejin Jeong from Pixabay

These distinct differences happen to be reasonably large. Most studies have found smaller differences. But here’s the thing. The actual psychological differences between cultural groups may be larger than those typically reported in academic journals. Here’s why.

Country and Culture Are Not the Same Things

Most studies that investigate the impact of culture on psychological variables are not cross-cultural studies per se. They are cross-national studies. The researchers don’t compare members of different cultural groups; they compare people living in different countries.

Using cross-national studies to investigate the impact of culture would be a perfectly good strategy if country and culture were synonymous, but they aren’t (Taras, Steel, & Kirkman, 2016). Most nations are not monocultural; they are multicultural. The United States, for example, is home to dozens of ethnic groups, each with its language, traditions, practices, and values. In culturally diverse societies, the country is an inadequate proxy for culture.

By definition, a culturally diverse group contains individuals of many different stripes. Consequently, the variability of the studied behavior is usually greater than in a monocultural group. Political opinions and voting choices, for example, are more variable in a group that includes Republicans, Democrats, and independents than they are in a group of Republicans only.

When we combine these three facts—(1) most psychological studies compare nations, not cultures; (2) many countries are culturally diverse; and (3) individual differences are greater in diverse groups than in less diverse groups—we can begin to see why psychological differences between cultural groups may be larger than we think.

The Determinants of Effect Size

The degree to which two cultural groups differ in terms of a psychological variable can be expressed precisely by a statistic called effect size. The effect size is a ratio that compares the difference between two group means (averages) with the overall variability in the groups. When the difference between the group means is large, and the individual differences within the groups are trivial, the variable of interest (in this case, culture) is said to have a large effect. The signal is loud and clear, in part because the background noise is negligible.

Now consider the situation that occurs in many psychological studies of cultural differences. Researchers devise a task of some sort and compare the responses of white American university students with the responses of East Asian university students. In cultural terms, white Americans and East Asians are heterogeneous groups. The first group may include Irish American, Mexican American, Italian American, and Lebanese American students who have grown up in different United States regions. The second group may consist of students from China, Hong Kong, Japan, Korea, Taiwan, and Vietnam. The mean difference between the two groups may be large or small, but the individual differences in both groups are probably large.

When the variability within national groups is large, the measured effect size will be smaller than otherwise. The cultural signal is weakened and more difficult to detect because it is masked by the background noise produced by individual differences.

The Pros and Cons of Studying Multicultural Groups

Astute readers can probably identify a critical benefit that comes from studying culturally diverse groups. Larger, more diverse samples are generally more representative of the overall population. As a result, we feel more comfortable generalizing empirical findings when they are derived from various samples of participants.

Less well understood is the cost of using multicultural groups to investigate the impact of cultural background on psychological functioning. Here’s an illustration inspired by an actual study conducted by Adam Cohen (2015).

Suppose we predict that Jews will judge a man leniently if he daydreams about having an extramarital affair with his attractive neighbor. We also expect that Christians will judge the daydreaming man more harshly. (In Christian theology, both actions and thoughts can be sinful. “But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart,” Matthew 5:28, New International Version. In Judaic theology, an act can be sinful, but a thought cannot.)

Further, suppose that we recruit hundreds of study participants. Some are Jewish (Orthodox, Conservative, or Reform) and some are Christian (Baptist, Catholic, Lutheran, Presbyterian, or Unitarian). Participants read our daydreaming scenario and make a moral judgment. As expected, Jewish participants as a group judge the man somewhat less harshly.

Would the difference in judgments be even larger if we compared only Orthodox Jews and Baptists? Probably, because these specific sects are presumably less variable than the others regarding their adherence to theological teachings.

Because most cross-cultural studies compare culturally diverse nations, and because increased variability within groups diminishes effect sizes, the empirical findings reported in academic journals may underestimate the real impact of culture on human psychology. Psychological differences between cultural groups may be larger than we think.


Cohen, A. B. (2015). Religion’s profound influences on psychology: Morality, intergroup relations, self-construal, and enculturation. Current Directions in Psychological Science, 24(1), 77-82.

Taras, V., Steel, P., & Kirkman, B. (2016). Does country equate with culture? Beyond geography in the search for cultural boundaries. Management International Review, 56, 455-487.

White, L. T. (2020). Culture Conscious: Briefings on Culture, Cognition, and Behavior. Hoboken, NJ: Wiley.

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