What leads people to develop a hostile, suspicious attitude toward minorities? Social scientists have a variety of theories. But recent research from Germany reports a mindset of intolerance can be triggered by a surprising catalyst: The discomfort that arises when one feels ostracized or excluded.

A research team led by social psychologist Nilüfer Aydin reports feeling excluded from a desirable social group threatens a person’s “sense of personal control.” In response, the researchers argue, some people attempt to reassert control by derogating stigmatized minorities.

Addressing these painful feelings is not “a panacea against radicalization and xenophobia,” the researchers write in the journal Group Processes and Intergroup Relations, “but it may be part of a broader strategy to address the problem.”

"When threatened by uncertainty, people identify more strongly with extremist or ethnocentric groups. Engaging in (political) radicalism may reduce feelings of uncertainty by restoring a sense of predictability and controllability in one’s social world."

Aydin and her colleagues provide evidence of this dynamic by describing four experiments. One of them began with the participants, 50 University of Munich students, reading one of three short stories about a person who had just started a new job. In one version, the new employee’s co-workers were welcoming and helpful; in another, they were actively hostile. In the third version, the central character was treated in a neutral way.

Then, after reading a news story about the proposed construction of a mosque in Munich, participants responded to a series of statements, including “Muslims should not practice their religion so publicly” and “Muslims should stay in their own group.” Finally, they were invited to sign a petition in support of the project.

The results: Those who were feeling a sense of social exclusion “reported stronger anti-Muslim attitudes.” Only 25 percent of people in that category signed the pro-mosque petition, compared to 37.5 percent of those who had read about social acceptance, or read a neutral scenario.

In another study, participants who wrote about a time they felt “severe social exclusion” were less supportive of the Munich mosque project than those who recalled a time they felt accepted, or (in the neutral condition) a time they felt ill. The researchers found similar results in an experiment measuring attitudes toward requirements for German citizenship.

In the final experiment, the 62 participants (again, University of Munich students) read one of the aforementioned new-job scenarios. Afterward, they wrote about either a “situation in your life in which you perceived yourself as particularly powerful,” or one where they felt “particularly powerless.”

Finally, they indicated their degree of agreement or disagreement with four statements, including “Foreigners increase crime rates” and “Foreigners take jobs away.”

Once again, a feeling of exclusion led to more negative feelings toward minorities, but this effect was erased when participants were given the opportunity to recall a time when they felt powerful.

“We conclude that helping people to restore a sense of control over their lives can prevent intolerance after social exclusion,” the researchers write.

Why would some people respond to feeling left out in this decidedly unhelpful way? Aydin and her colleagues point to Social Identity Theory, which suggests our sense of self is largely based on our group membership.

“When threatened by uncertainty, people identify more strongly with extremist or ethnocentric groups,” they write. “Engaging in (political) radicalism may reduce feelings of uncertainty by restoring a sense of predictability and controllability in one’s social world.”

Their study raises an interesting question: Could it be that hard-core haters of President Obama are driven, at least in part, by real or imagined fears of exclusion as the nation’s racial and ethnic makeup evolves? These results suggest the idea is very much worth studying.