Presidential candidate Ben Carson recently said he didn’t think a Muslim should become President of the United States, adding, “I do not believe Sharia is consistent with the Constitution of this country.”

This kind of argument has an obvious precedent: the widespread opposition to the idea of a Catholic president before John F. Kennedy’s election in 1960. As is the case with Muslims now, many Americans in those days wondered if Catholics could truly fit in with mainstream U.S. society, and whether a Catholic leader could put the interests of his country ahead of potentially conflicting religious dictates.

In a paper published in 1964 based on data collected before the election season, Richard A. Lamanna and John B. Stephenson looked at how anti-Catholic prejudice influenced young, educated voters’ choice between the two candidates, Nixon and Kennedy.

The authors surveyed 141 non-Catholic graduate students at the University of North Carolina. They asked for the respondents’ opinions on statements designed to test their attitudes toward Catholic individuals (for example, “It is sometimes all right to ban Catholics from certain jobs”) and the Catholic Church (e.g. “The Catholic Church opposes free speech, free press, and free inquiry”).

To a modern reader, the level of prejudice the surveys found against Catholics is striking. Thirty-five percent held highly negative attitudes against both Catholics and the church. Another 26 percent were highly biased against either the church or individuals (but not both), while 38 percent did not express much bias toward either group.

Of all those surveyed, 59 percent said they would vote for Kennedy over Nixon. But, not surprisingly, JFK only received 30 percent support by those who identified as deeply anti-Catholic. This made an anti-Catholic attitude an even stronger predictor of a Nixon vote than party affiliation did.

The researchers also asked an additional set of questions about the respondents’ knowledge of Catholic doctrine. The responses split the group down the middle, with 51 percent turning out to be well informed, while 49 percent were less knowledgeable. Those who knew a lot about the teachings of the church were less likely than average to be anti-Catholic. However, the small minority of people who were both knowledgeable about Catholicism and highly prejudiced against Catholics (a total of just 17 respondents) were by far the least likely to vote for Kennedy. Only 18 percent of that group picked JFK, compared with 36 percent of those who were equally prejudiced yet knew very little of Catholicism itself.

The authors concluded that “there is such a species as a ‘knowledgeable bigot,’” but that prejudice was more likely to stem from ignorance than from informed opinion.

The fact that bigotry was more common among the uninformed—not to mention the decline in anti-Catholic prejudice in the 50 years since this paper was published—should give us some reason to think that anti-Muslim bias may decline as well.