WEIRD is the acronym three social psychologists devised to describe people living in Western, Educated, Industrialized, Rich, and Democratic societies. In 2010, the trio—Joseph Henrich, Steven J. Heine, and Ara Norenzayan, all based at the University of British Columbia—reviewed decades of behavioral science research and concluded that "members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans." Scientists, they concluded, "need to be less cavalier in addressing questions of human nature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity."

One big distinction between WEIRD people and the rest of humanity, they argued, is a tendency to think analytically instead of holistically. Broadly speaking, holistic thinking is oriented toward context, preferring to predict behavior using situations and circumstances. Analytic thinking detaches objects from contexts, preferring to use categorical rules to explain and predict behavior. The research the trio referenced included a 2001 study in which American and Japanese subjects were shown a photograph of a wolf in a forest. The Americans were more likely to remember having seen the wolf even when it appears against a new background, such as a desert.

A 2010 paper in Current Directions in Psychological Science argued that these distinct modes of thought stem from differences in social orientation. Every person can and does switch between these two modes of thought. But people are more likely to think analytically when their culture endorses "self-direction, autonomy, and self-expression" and views the self as "bounded and separate from social others." People tend toward holistic thinking when their culture supports an interdependent, connected view of the self and emphasizes fitting in and harmony more than self-expression.

Analytic thinking is prevalent in the West, but it isn't monolithic. A team of researchers associated with the New York University social psychologist Jonathan Haidt wondered if the distinction between holistic and analytic thinking might be relevant to America's notorious "culture war." The team including University of Virginia social psychologists Thomas Talhelm and Shigehiro Oishi, and Chinese psychologists Xuemin Zhang, Felicity Miao, and Shimen Chen report the results of five different studies in a recent for the Personality and Social Psychology Bulletin, "Liberals Think More Analytically (More 'WEIRD') than Conservatives."

The Haidt team notes that previous research usually did not pull apart the messy strands of economic and social politics that make up people's political identities. This leads to a problem they call the "libertarian exception." Libertarians have often been mixed in with conservatives, yet conservatives are the most socially interdependent group and libertarians are the least interdependent. "Because libertarians are so individualistic, they should be on the extreme analytic end of the spectrum," the researchers note. "Indeed, libertarians score the highest of any political group on a measure of 'systemizing' and the lowest on 'empathizing'. Mixing libertarian analytic thought with holistic conservative thought weakens the liberal-conservative differences."

To take account of libertarian thinking, the researchers separate "social politics," involving issues such as recreational drug use and gay marriage, from "economic politics," involving issues such as taxes and regulations. They found that differences in analytic versus holistic thinking account for differences in opinions over social issues, but not economic issues.

In the first study, university students were sorted by social politics on a seven-point scale ranging from very liberal to very conservative. They then were shown three items and asked to indicate which two of the three are most closely related. For example, they might see pictures of a scarf, a mitten, and a hand. Holistic thinkers tend to choose the more relational pairing (mittens are worn on hands), whereas more analytical thinkers tend to pair more categorically (the mitten and scarf are both winter clothing). Very liberal student participants choose relational pairings 61 percent of the time, while very conservative participants choose them 78 percent of the time.

Another study used Internet participants with a mean age of 35; it also included a libertarian option. It similarly found a distinction between liberal and libertarian analytic thinking and conservative holistic thinking, but all three groups tended to be more analytic than the college students. About 35 percent of very liberal participants chose relational pairings, compared to 45 percent of very conservative ones.

Interestingly, when the researchers did not separate social and economic politics, libertarians were the most analytic group and moderates were the least. "Consistent with their creed that people should stick to their own business and not interfere with the lives of others," the researchers wrote, "libertarians thought more like individualistic Westerners than collectivistic Easterners."

The researchers also went to China to test their social orientation hypothesis. They already knew that Mainland Chinese tended to score on the holistic end of the spectrum, but they wanted to see if differences in thinking styles had emerged in a rapidly urbanizing population. They asked Chinese university students at six sites to do a triad task like the one from the first study.

The political spectrum among the Chinese subjects ran from very liberal to slightly conservative. Liberal participants paired the objects relationally 70 percent of the time, while slightly conservative ones did so 79 percent of the time. Compare this to very liberal American students, who paired relationally 61 percent of the time, whereas very conservative Americans did it 78 percent of the time. So both Chinese and American conservatives have about the same tendency to think holistically. [Note, though, that the Chinese 78 percent were slightly conservative and the American 78 percent were very conservative.]

Next, the researchers wanted to see if a bit of "thought training" might change the subjects' orientation. In this experiment, American university students were once again sorted by social politics and economic politics. Then they were told to classify objects—say, a janitor, a mop, and a jackhammer—by either abstract categories or relational condition. The students then read purported news articles, one opposed to welfare programs and another opposed to mainstreaming special education students. Note that welfare spending in the U.S. is a partisan issue, whereas mainstreaming is far less so.

The scientists predicted that the analytic version of the task would push people to form more liberal opinions and that the holistic training would induce them to generate more conservative opinions. The thought training manipulation produced just that result. "If this were a vote, the liberal [welfare] plan would have won after we had people think analytically (64 percent support) and lost after we had people think holistically (38 percent)," they report. The mainstreaming article had no effect on political orientation.

Finally, the Haidt team did a similar thought training study using university students and visitors to YourMorals.org. Participants sorted by social and economic political views once again were instructed to classify items either relationally or categorically. Afterward, they read two fabricated news stories, one proposing to send convicted drug users to college for free and another advocating free trade. In this case, 52 percent of holistically manipulated participants would have supported sending convicted drug users to college, whereas 70 of the analytically thought-trained would have done so. The "training" had no effect on responses to the free trade article, a result that fits the earlier findings that cultural thought style is more strongly related to social politics than economic politics.

The researchers conclude that conservatives and liberals really do think about the world as though they come from different cultures. The obvious resolution to this conflict is for American liberals and conservatives to join with their libertarian comrades and think even more WEIRDly about freedom.