1. Why the acronym WEIRD?


The acronym WEIRD—Western, Educated, Industrialized, Rich and Democratic—aims to raise people’s consciousness about psychological differences and to emphasize that WEIRD people are but one unusual slice of humanity’s cultural diversity. WEIRD highlights the sampling bias present in studies conducted in cognitive science, behavioral economics, and psychology. When my colleagues and I coined the term a decade ago, our goal was to encourage experimental behavioral scientists to diversify their sampling and avoid generalizing from a peculiar subgroup to the entire species. Only by recognizing this diversity can we begin to rewrite the textbooks in ways that provide a more inclusive picture of the psychology and behavior of Homo sapiens.


2. And yet you caution readers not to set up a WEIRD vs. non-WEIRD dichotomy as they read your book. Can you expand on that?


That’s right. While WEIRD should raise people’s consciousness about psychological differences, it’s not meant to suggest a simplistic dichotomy or binary worldview. After all, psychological variation is both continuous and multidimensional. It varies at all levels, sometimes between regions, provinces, villages, or even between generations, not just among nations. Using data from Italy and China, for example, I explain why adjacent provinces show psychological differences in everything from analytic thinking to trust in strangers.


3. What are the big questions this book aims to answer?


I’d say there are three, and they are interrelated. First, how can we explain the psychological diversity that has now been documented around the world? Second, why are the WEIRD populations, who so dominate what we know scientifically about “human” decision-making, motivation and reasoning, psychologically different? And finally, does the shifting psychology of Europeans over the last millennium help us understand the massive military and commercial expansions of these populations around the globe after 1500 and the economic eruption, known as the industrial revolution, after 1750 CE?


4. What’s the connection between culture and psychology?


Our minds are frequently understood using a misleading digital computer metaphor, with our brains and psychological processes as the hardware and our cultures—our values, customs and know-how—as the software. However, research in neuroscience and related fields has now made it clear that the process of learning, including learning from others, as we navigate through our culturally-constructed worlds changes our brains, hormones, and other aspects of our biology. Culture thus not only shapes whatwe think, but how we think as well as how we reason and perceive the world. The institutions, technologies, practices and languages that people experience while growing up, and throughout their lives, create diverse cultural psychologies.


5. Where did WEIRD societies originate?


In short, WEIRD groups were born out of a peculiar set of religious prohibitions and prescriptions by the medieval Catholic Church, which re-organized European kinship in ways that altered people’s social lives and psychology, ultimately propelling the societies of Christendom down a historical pathway not seen elsewhere.


These dictates (especially the expanded prohibitions on incest) reshaped European families and in turn people’s cultural psychology and communities in ways that opened a pathway to the political, economic, and social institutions of the modern world.


I should add that it was the taboos of one branch of Christianity, not the entire Judeo-Christian Tradition, that altered kinship and ultimately psychology. To illustrate this, I show how ecological factors have shaped family structures in ways that create similar, though less extreme, psychological variation within China and India, well outside of Europe and away from Christianity.


6. What are the main psychological differences among populations?


When relational bonds became fewer and weaker, individuals needed to forge mutually beneficial relationships, often with strangers. To accomplish this, they had to distinguish themselves from the crowd by cultivating their own distinct set of attributes, achievements, and dispositions--individualism.


Success in these individual-centered, proto-WEIRD worlds grew to favor the cultivation of greater independence, less deference to authority, more guilt, stronger use of intentions in moral judgments, and more concern with personal achievement. Success became less bound by tradition, elder authority, and general conformity. WEIRD individuals have to “sell themselves” based on their personal attributes, specialized abilities, and dispositional virtues, not primarily on their friendships, lineages, or family alliances.


7. What do you see as the most important take-home messages from this book?


It is no longer tenable to continue pretending that all populations are psychologically indistinguishable or that cultural evolution doesn’t systematically modify how people think, feel, and perceive. And knowing this changes our understanding of who we are and where our most cherished institutions, beliefs, and values come from.


After all, major institutions like democracy, constitutional law, and science didn't spring from the minds of Enlightenment thinkers after they threw-off the shackles of religion and “discovered” rationality and reason. Instead, these concepts evolved over a long-process of myopic groping, and through an interaction with a particular cultural psychology and family structure. They reflect the hidden dynamics of a particular pathway of cultural evolution.


Formal institutions, social norms and cultural psychologies coevolve in mutually re-enforcing ways over centuries. Such interactions explain why one can’t simply transplant the political, legal or religious institutions from one population into another population—as was common under colonialism—and expect them to operate in similar ways. Instead, such institutional-psychological mismatches often disrupt people’s identities, create moral conflicts, breakdown the kin-based institutions that provide social security, and foment social turmoil.


Finally, in discussing the massive economic expansion of the last few centuries, the book shows how certain psychological traits—e.g., trust in strangers, tolerance of differences, rejection of tradition, and an openness to novelty—spurred the acceleration of innovation by creating sprawling social networks through which diverse ideas, practices, techniques and concepts flowed and recombined. Communities and organizations that cultivated greater psychological and cultural diversity—however modest by modern standards—thrived and outcompeted their competitors. In other words, ethnocentrism is the enemy of innovation.


8. Aren’t all the psychological traits you describe for WEIRD people “positive”?


People sometimes see it that way at first, but this simply expresses their own value judgments and cultural insularity. We often culturally value the psychological traits that we cultivate in ourselves. However, I hope to hold a mirror up to help readers understand the virtue of psychological diversity, of the value of different ways of thinking and feeling. Most saliently, WEIRD people are highly individualistic, which means we are overconfident, self-obsessed and even more suicide-prone. WEIRD people also tend to be highly analytical in their thinking. That is, we focus on individuals and their properties at the expense of relationships and backgrounds. But, of course, sometimes mending a friendship or spotting a problem requires attending to the contexts and to the social ties involved. Similarly, WEIRD people are, relative to many other populations, less willing to help their family and friends at a cost to themselves or strangers. WEIRD people also have some irrational decision-making biases—such as what’s called “the endowment effect,” which explains why sellers are so often disappointed in how much their home is worth—we overvalue our own stuff.


9. What are the core aspects of psychology that drove the so-called “prosperity” you describe?


Again, I see innovation as the primary driver of the rising incomes and life expectancies observed over recent centuries. Key to understanding where innovation comes from is the idea of the collective brain, which expands when larger and larger communities of strangers interact, trust each other regardless of their backgrounds, share ideas and work together. This places a premium on trust in strangers, toleration of ethnic and religious differences and individual mobility, which propels people to seek out new, mutually beneficial relationships. For instance, I look at research showing how immigration to the U.S. during the era of mass migration propelled much of the innovation. U.S. counties that ended up with more immigrants generated more rapid rates of innovation and were subsequently more prosperous. I track the same patterns back into pre-industrial England and France to show how greater tolerance of differences, openness to foreigners and trust in strangers propelled more rapid innovation and economic growth. It also led to the end of famines.


10. What would you say to those who might argue that, especially given the way Western countries have responded to the current pandemic, prosperity and success aren’t words they’d associate with the West?


Since at least Adam Smith, economic historians and other researchers have sought to explain why incomes vary across populations, began rising so rapidly after 1750, and started earlier in some places. While it’s certainly subjective, many would agree that societies with greater incomes per person, longer lives, fewer famines and lower rates of infant mortality are more “prosperous.” My efforts to tackle this question complement a long list of other researchers seeking to tackle this puzzle in various ways, including historians like Ian Morris, political scientists like Francis Fukuyama, economists like Daron Acemoglu and James Robinson, and, perhaps most famously, evolutionary biologists like Jared Diamond.


Alternatively, one might wonder about the history of representative democracy, modern law codes, universal state-funded schooling, notions of human rights, or the institution of science. Where did they come from and why? Or, one might ask why were Europeans able to spread across the globe after 1500, dominate and enslave other populations, and impose their rule? Why didn’t this happen the other way around? If, in 1000 CE, one had asked the question of who’s institutions and economic systems would dominate the world during the second half of the second millennium, most people would have bet on China or the Islamic world. Of course, the third millennium is shaping up rather differently.


The current global pandemic showcases psychological diversity in a powerful way and provides enormous insights into the diverse responses of different populations. Consider the psychological characteristics individualism, tightness (lots of constraining social norms) and trust in government. A poor response to the pandemic—e.g., Texas—can be predicted by high individualism, low tightness and low trust in government. Individualists don’t like to be told what to do (e.g., wear a mask), especially if they distrust the government, and a certain “looseness” means that others can’t shame deviants into compliance. Places like Germany are high on individualism too, but are also “tight” and have high trust in government, so they are able to fight the pandemic more effectively. Some populations in East Asia are socially tight, high on obedience to authorities (including governments), high on conformity and low on individualism (no desire to impress others with their independence), so they are well-positioned psychologically to fight the pandemic.


What my book does is ask the question: why do populations vary along these different psychological dimensions and how has this changed over history? This question has almost never been asked, and this lack of focus on psychological differences shrouds our understanding of the world’s diverse response to the pandemic.


In the book, I also explore how shocks like earthquakes, wars, hurricanes and other natural disasters shape people’s psychology and ultimately cultural evolution. Such evidence will be crucial for understanding how the pandemic will shape people psychology, and the direction of cultural evolution in the future.


11. Many scholars have argued that Western success was built on imperialism and extractive economic policies. How do these kinds of forces relate to the psychological and cultural differences you're describing?


It’s absolutely true that imperialism, extractive economic policies, war, genocide and slavery were central to the European expansion after 1500. The question is why did the Europeans during this epoch—but not before—have the commercial interest as well as the military, technological and organizational capacities to impose on societies around the world? I lay out how the interaction between people’s psychology, family structure, and the rise of new economic and political institutions create the conditions for the European expansion. Considering the social psychology at play helps us to more deeply understand the emergence of imperialism, extractive economic policies and many other features of these societies.


  1. course, keep in mind that after integrating aspects of Western civil codes that transformed marriage and family in places like Japan, South Korea and China, non-Western populations synthesized their own unique cultural and psychological configurations that sometimes similarly spurred rapid economic growth, effective governments, and innovation. These non-WEIRD cultural complexes do incorporate ideas and institutions forged in medieval and early modern Europe; but as I show, this is a two-way street going back millennia: Europeans inhaled organizational forms, ideas, concepts and technologies from populations around the world. For example, key elements of the university as well as numbers, scientific ideas (controlled experiments) and many technologies were acquired from Central Asia, China, India, South America and the Islamic World.


12. How are cultural-psychological traits passed on and sustained, generation after generation? Does your research account for immigration? What happens when people emigrate from say a non-WEIRD society to a WEIRD one?


Immigration is central to my exploration in a few ways. First, people culturally learn from many others, besides their parents and families, so immigrants culturally and psychologically assimilate to their new societies. This was crucial in medieval Europe in many ways, as rural people immigrated into growing cities and acquired new sets of norms along with novel ways of thinking. Today, most Americans who trace their heritage to diverse non-European populations around the globe—such as in Asia, Africa and South America—are nevertheless psychologically WEIRD, indistinguishable from Americans of European descent. Second, as I noted above, certain aspects of psychology open people to immigrants and interaction with diverse communities, which ultimately drove innovation and economic growth.


13. What do you say to those who theorize that movements like the Enlightenment or the Reformation or the Industrial Revolution—or even technology or imperialism—might have been the source of WEIRD characteristics more than the decisions of the medieval Catholic Church?


Each of these likely plays a role, but it was the initial social and psychological changes spurred by the Church’s peculiar policies on marriage and the family that started the avalanche, well before these much later events. In the book, I turn the tables on these explanations by asking where the ideas of the Enlightenment thinkers came from (what kind of mind likes such ideas?), what made such highly individualistic religions such as the Protestant faiths attractive (Individualism came first), and what allowed the industrial revolution to take off in the first place?


After all, if it was affluence that drove a WEIRDer psychology, then it should have been Europe’s aristocrats that fueled the entrepreneurial engines of the Industrial Revolution. Instead, it was the urbanizing individualists, artisans, and clergy in the middle class who invested in the first joint stock companies and invented the printing press, steam engine, and spinning mule. The elites, by contrast, just got themselves repeatedly into debt by spending on personal extravagance instead of investing their wealth and saving for the long run.


14. By connecting psychological differences to economic outcomes, could these views be twisted to support a white supremacist agenda?


Sadly, we live at a time when facts are routinely twisted to support oppressive and inhumane political agendas – and those ideas are easily and widely broadcast – so yes, of course that is possible. the science very clearly does not support their worldview, and I fear that the field of science plays into dangerous hands when it fails to tackle such questions head on. The best antidote for pseudo-science is real science.


Consider this:


The evidence shows that differences in various aspects of psychology pattern with certain economic outcomes. The economic literature, for example, confirms clear links between psychological traits like individualism and trust and economic outcomes like income and innovation. Naturally, people wonder where these psychological differences came from and what the connection is to prosperity. If you are a white nationalist, you have your answers, they are genetic and related to race, or that there is something “superior” about Western culture.


Currently, there’s no substantive scientific response to such explanations, at least in accessible trade books and in the public discourse. The silence regarding how to explain links between psychology and economics has created an intellectual and scientific vacuum, which is rapidly filled with racist ideologies and politically-motivated pseudo-science.Until now, there have been no contributions within the broadly accessible public discourse that provide a detailed and empirically-grounded cultural and historical explanation for the psychological and economic differences found in the world. White supremacists have pointed to this gap—the absence of scientific explanations for global diversity—as evidence for their view—suggesting that the scientists are silent because they don’t have a non-genetic alternative explanation.


I hope my book fills this intellectual void with a deep understanding—rooted in biology, psychology and economics—of the explanation for these patterns, and how off-the-mark those claiming genetics or “superior” cultures are. The central ideas in my book help explain differences in both psychology and economic outcomes between European regions that are side-by-side within the same country—a fact that demolishes imaginary notions of an essentialized “white race” or ‘European culture’. In explaining the acceleration of innovation that has driven so much of the world’s economic growth over the last three centuries, I focus on the power of the collective brain and psychological traits related to trust in strangers, tolerance of those with different customs, and an openness to the world has fueled innovation and economic growth, first in Europe and later in the U.S.


For a related discussion of how immigration to the U.S.A. has propelled American innovation for over the last two centuries, see my essay in This View of Life: https://thisviewoflife.com/why-immigration-drives-innovation/