If you are an American, in all likelihood you have been exposed to Russian propaganda online. As we now know, in the months before the 2016 presidential election, Facebook estimates that 126 million U.S. users have seen posts, stories or other content created by Russian-government-backed accounts, and an additional 20 million have been exposed to this Russian content on Facebook-owned Instagram. A similar picture emerges from Twitter and YouTube. Russia has weaponized the social media to spread rumors, conspiracy theories and emotion-stirring images in a coordinated effort to radicalize the USA from within.

Americans were not their only target: former Soviet republics (Ukraine, Georgia, Estonia, Lithuania), as well as countries of the EU (Poland, France, Germany) have been subjected to the same treatment. In different languages, Russian trolls used the same tactics: planting and amplifying divisive messages, posting fake or doctored photos and made-up stories to stoke (vaccinations are killing your kids) and anger (immigrants are coming for your jobs).

But Americans fell for the Russian lies at a much higher rate. Researchers found an average of 1.73 likes, retweets or replies for Russian trolls’ posts in Russian or any language other than English; for English-language posts, the rate was nine times that high (15.25). Americans, it turned out, were easy targets for the Russian propaganda.

The American social media giants scramble to defend against the onslaught of Russian troll attacks. One result of their efforts makes it possible to now check if you personally were exposed to the Russian propaganda.

What remains unclear is why Americans were so much more vulnerable than other targets.

An answer proposed by the study’s authors was that the former Soviets were “immunized” against the Russian propaganda. Because of their history, they expect to be lied to, and so are generally more cynical than Americans. This is an explanation from the realm of Cultural Psychology. There may be some truth to it. As a former Soviet citizen, I can attest to the imbued cynicism.

But can’t be the whole answer.

If cynicism were enough to immunize against propaganda, then we should expect Russians to be at the Kremlin’s recent portrayals of supposed Ukrainian against Russia, or of supposed NATO plans to attack Moscow. Instead, cynical as they are, most Russian seem to believe the Kremlin-directed propaganda that targets them. The cynicism, therefore, is not enough to understand what makes Europeans less susceptible than Americans to Russian propaganda.

What if we try another explanation, not from cultural psychology, but from mass psychology?

Jon Haidt calls the human ability to forsake individual interests in the name of group interests the hive mind. We have a kind of hive switch built-in, Haidt suggests, that can be flipped, turning us from rational individualists into selfless group players. This ability, he argues, has evolved through natural selection, because humans live in groups, and groups can persist only when some members are willing to give up their interests, and even their lives, for the benefit of others.

When the hive switch is turned on, we turn away from our individual toward a mass identity––ethnic, religious, or national. When the hive switch is turned on, we can become radicalized: more accepting of violence in the name of the large impersonal collective that is our mass identity.

That’s what the Russian trolls attempted: to set our mass identities at odds, radicalizing blacks against whites, Caucasians against Latinos, WASPs against Jews, and Democrats against Republicans. Through the mass psychology lens, the question becomes, why was American mass identity more easily radicalized through social media than, say, Ukrainian or Estonian mass identity?

Mass identities are social constructs. We need to know what our fellow X (Americans, Jews, Ukrainians) are up to, and up against. We need information to maintain and nurture our mass identities. One big difference between the US and European countries is availability of this kind of information.

Physically, Americans are more isolated than Europeans. The average population density in the USA is 92 residents per square mile, versus about 143 residents per square mile in Europe. Most U.S. residents (70%) live in detached houses in small towns and suburbs where they have to drive to get to work, school, or grocery store. Compare this with only a third of Europeans living in detached homes. And more Europeans ride public transport or bike or walk to work, school or grocery store.

Americans work more hours and take fewer vacation days than Europeans. Europeans are more willing to give up money for leisure than Americans. American preferences for personal cars, detached homes and more income result in long and lonely commutes from home to work, with less time to socialize and fewer venues for socialization. Taken together, these factors contribute to the stark difference in loneliness between Americans (46%) and Europeans (6%).

When real-life social interactions are fewer, virtual interactions have more scope to define and radicalize mass identity. Seventy-one percent of American Internet users report using social media, as compared with 58% in France, Italy and Spain, and 46% in Germany and Poland. Russian propaganda masters pounced on the opportunity use social media to define and mobilize American mass identities. Because Americans are more dependent on social media, Russian propaganda succeeded beyond anyone’s expectations. made Americans vulnerable to social media manipulation.

Physical isolation is a simple demographic explanation for a complex psychological phenomenon, but the link is not hard to see. The number of people we run into predicts how many social connections we form. Researchers studying undergraduate friendships discovered the physical location of one’s dormitory room determined how many friends one had at the end of the year (Latane, et al., 1995). Propinquity, or degree of exposure to people, predicted popularity.

As we ran into fewer people, we have fewer friends. Americans’ number of close confidants dropped from three to two over the past 25 years, nearly tripling the degree of social isolation. With fewer friends and fewer social interactions, we become lonelier, seeking virtual substitutes through the Internet. And that’s where Russian trolls dwell.

American vulnerability to social media propaganda points to a need for counter-measures. One is increasing public awareness about social media’s radicalizing potential. Building up healthy cynicism about online political content can help immunize Americans against Russian ruses and against others trying the same techniques. Cynicism should be easier in a time when new investigations of political malfeasance are announced weekly.

Another countermeasure might be government oversight of the social media. The reach and speed of the Internet allowed hostile foreign actors to spread radical ideas far and wide among us. Russian propaganda attacks may help bring an end to the Wild West era online. Algorithms and safeguards to detect and avert similar attacks in the future may be required, though preserving freedom of speech will not be easy.

Finally, we should all get out more. Loneliness is a dangerous condition, with health consequences as dire as a 15-cigarettes-per-day smoking habit. Until recently, we could dismiss loneliness as a personal problem. But the success of the Russian mass identity manipulations shows that it can be a political problem as well.

It would serve our national interests to spend more tax dollars on events that bring people together. During sports events such as soccer world cup, football playoffs or rugby world cup, suicide rates drops by as much as 10 percent, with the greatest drop among men aged 30-44. Especially for sports fans, these spectator events create social exposure and opportunities for socialization even after the games are over. But sports are not for everyone. Some people (myself included) feel more, not less , where it comes to spectator sports. But the variety of mass social gatherings is broader than sports. In addition to their already more connected home and work lives, Europeans encounter a wealth of socializing events: regular street fairs, free music performances, open-air art exhibits, and even impromptu yoga and dance sessions. We could use more of those. Nations that play together stay together against mass identity manipulations.