LEVERETT, Mass. — Paula Green has spent much of her life working on conflicts abroad. In places like Bosnia, Rwanda and Myanmar, Dr. Green, an American psychologist, brings together survivors of war, helping them see past their differences so they can live with one another again.

But recently, she began seeing some warning signs in the United States, flashes of social distress that she recognized from her work abroad, and after 29 years of peacemaking in other places, she decided to turn her lens on her own society.

“People are making up stories about ‘the other’ — Muslims, Trump voters, whoever ‘the other’ is,” she said. “‘They don’t have the values that we have. They don’t behave like we do. They are not nice. They are evil.’”

She added: “That’s dehumanization. And when it spreads, it can be very hard to correct.”

Dr. Green is now among a growing group of conflict resolution experts who are turning their focus on the United States, a country that some have never worked on. They are gathering groups in schools and community centers to apply their skills to help a country — this time their own — where they see troubling trends.