J.K. Rowling once said, "The Potter books in general are a prolonged argument for tolerance, a prolonged plea for an end to bigotry."

And now there's science to back her statement up.

A recent paper in the Journal of Applied Social Psychology outlines three studies that demonstrate how reading the Harry Potter series can improve young people's view of stigmatized groups like immigrants and homosexuals.

Harry Potter and the battle against bigots

Prejudice is a recurring theme in Rowling's best-selling books. There's prejudice against muggles (non-magical people), prejudice against wizards without "pure blood," and prejudice against other magical species, such as centaurs and goblins.

Throughout the series, Harry and his friends stand up for marginalized groups and fight for equality, so researchers were curious if the boy wizard's morals were rubbing off on young readers.

To test if reading the books could reduce prejudice, researchers first had 34 Italian fifth-graders fill out questionnaires to assess their attitudes toward immigrants.

For the next six weeks, the students read selected passages from the Harry Potter books and discussed them. Half of the group read and discussed parts of the book that dealt with bigotry, while the other half read passages unrelated to prejudice.

Then the children again answered questions about their feelings toward immigrants. They also listed how many Harry Potter books they'd read and indicated how much they wanted to be like the boy wizard.

Researchers found that the students who had discussed the excerpts about prejudice and felt an emotional connection with Harry, showed "improved attitudes toward immigrants."

The second study involved 117 Italian high-school students who were asked how many of the books they'd read and whether they identified with the boy wizard.

In what they were told was a separate study, the students were then asked to share their attitudes toward homosexuals.

Findings revealed that those who'd read more of Rowling’s books were more accepting of homosexuals — but only if they felt connected to Harry.

The third and final study discussed in the paper assessed British college students' attitudes toward refugees.

This time, identification with Harry wasn't linked with lower levels of prejudice, but researchers point out that older groups are less likely to view the boy wizard as a role model.

However, researchers did find a similar dynamic at work. This time, the key was to what extent the study participants identified with Voldemort, the books' villain. Those who expressed less of an emotional connection with Voldemort had "improved attitudes toward refugees."

In conclusion, the paper credits the books with enabling readers to view society from the perspective of a marginalized group.

The Power of Potter

There's also evidence that Harry Potter's message of acceptance and equality has inspired youth to get involved in charity work and even influenced the outcome of U.S. presidential elections.

Anthony Gierzynski, a political science professor at the University of Vermont, believes the moral lessons in the Harry Potter series "played a small but not insignificant role" in President Obama's elections in 2009 and 2012.

In his book "Harry Potter and the Millennials: Research Methods and the Politics of the Muggle Generation," he argues that the lessons fans internalized about tolerance and diversity influenced their votes.

"Whether it is ignoring status as a pure-blood to judge individuals on the quality of their character, or simply courtesy toward any person regardless of their appearance or societal position, the tale of the boy wizard teaches it is good to reserve judgment, to be open to those who are different," he writes.

And the Harry Potter Alliance, a coalition of fans who fight real-world "dark arts" like inequality, illiteracy and human rights violations, prove just how effective young people moved by the books' message can be.

Since it was founded in 2005, the group has donated books and canned goods to charities, petitioned Warner Brothers to prove its Harry Potter chocolates are produced without the use of child labor, and raised hundreds of thousands of dollars to protect citizens in Darfur, among other projects.

The nonprofit often quotes Rowling to state one of its core beliefs: "We do not need magic to change the world. We carry all the power we need inside ourselves already. We have the power to imagine better."

Related on MNN: