On the eve of a planned speech by Mitt Romney to discuss his Mormon faith comes a new scientific poll that found Americans are more biased against Mormons than they are against black people or women.

The study, which was released yesterday, was conducted by three professors from Claremont Graduate and Vanderbilt universities.

In addition to its finding that bias against Mormons is significantly more intense among the public compared to bias against women and black people, the poll found that bias against Mormons is especially pronounced among conservative Evangelicals. That group’s bias against Mormons rivals its bias against atheists.

The study said that only about half the nation claims to even know a Mormon or to know that Mr. Romney, a Republican and former governor of Massachusetts, is Mormon.

The extent of the bias against Mr. Romney was moderated if the individual already knew that he was Mormon, the study said.

Earlier this year The Chronicle Review published a sampling of opinions by academics, bloggers, and others on the Mormon Factor in the 2008 presidential election — and whether Mr. Romney can overcome it.