As a young teenager in Germany in the early 1990s, Jens Hainmueller watched in shock as TV reports showed people cheering while they threw Molotov cocktails into the houses of immigrant asylum seekers. The images of burning people running from the homes remain vivid in his memory.

Now a political science professor at Stanford, Hainmueller focuses on how societies integrate immigrants, what policies could prevent violence, and in particular why people see immigrants as a threat. He believes anti-immigrant sentiment is born not out of economic anxiety, as some previous research has shown. Instead, his research shows, people who oppose immigration seem to fear that the newcomers will change the group’s identity and fail to contribute to the country as a whole.

“Previous research found anti-immigrant attitudes came from the fear ‘They may take my job away,’” says Hainmueller, who recently surveyed more than 100 studies of attitudes toward immigration with Georgetown’s Daniel J. Hopkins. The survey, and Hainmueller’s own research, “shows that it is something like nativism that drives this deep-seated opposition.”

Hainmueller mined large public opinion surveys to discover people aren’t any more concerned about immigrants who compete with them economically. For example, a 2013 U.S. survey of more than 4,000 workers in 12 industries ranging from meatpacking to finance showed that everyone, regardless of position or industry, consistently expressed more support for immigrants with higher skills. If economic anxiety were really the motivating factor for people’s immigration fears, you would expect to see these workers express less support for immigrant workers in their own industries or professions, who could perhaps be eligible for the same jobs.

Switzerland’s Experience

Another interesting illustration of the emotionally rooted response toward immigrants can be found in Switzerland. In that country, individual immigrants can become citizens based on the votes of native Swiss who live in that immigrant’s region. By examining voting records, Hainmueller was able to compare situations in which Swiss citizens were asked to vote, for instance, on whether to admit as a citizen a person from Turkey or the former Yugoslavia or a person from Germany or Italy.

He found that immigrants from countries more distant culturally from Switzerland were 40% less likely to be approved as immigrants from more similar countries, even if they spoke the same languages and held similar occupations.

These findings, Hainmueller says, suggest that native-born people’s attitudes are rooted in questions of identity, not personal economics.

In fact, Swiss authorities tried to counter this attitude and inculcate a greater acceptance of immigrants through an ad campaign showing immigrants as similar to natives and contributing to Swiss life. One of the television commercials showed an African immigrant coming to work as a train operator, arriving steady as a clock each day. Both trains and timing are central to Swiss identity.

Language Education Is Key

One intriguing question is how much an immigrant’s characteristics can lessen the threat to identity that some people feel. For instance, native-born people’s attitudes are less affected by skin tone or origin than by language, Hainmueller says.

“People may be less likely to develop an anti-immigrant attitude based on immutable qualities,” he says. “You can’t change your skin color, but you can learn English.”

Impact on Policy

This research has implications for policymakers. If you believe anti-immigration sentiment is rooted in anxiety about jobs, you might think you can quell opposition by promising more jobs or payments for displaced workers.

But Hainmueller’s research shows policymakers might do better to show native-born people that immigrants are not as different as they might seem, and therefore not a threat to identity.

Also, Hainmueller says, policymakers might be wise to highlight the many positive contributions that immigrants make to the country as a whole. For example, immigrants or their children founded 40 percent of America’s Fortune 500 companies, even though immigrants make up only roughly 10% of the population, based on a 2010 report of the Partnership for a New American Economy.

“It is difficult, but policymakers could think of ways to show native-born people that immigrants are not as different as they might seem to be — and that instead of being a threat to cultural identity, they can be contributors to the society as a whole,” he says.

Hainmueller has established the Stanford Immigration and Integration Policy Lab to drive more research into these attitudes.