Numerous surveys have found that professors, especially those in some disciplines, are to the left of the general public. But those same -- and other -- surveys have rarely found evidence that left-leaning academics discriminate on the basis of politics. So to many academics, the question of ideological bias is not a big deal. Investment bankers may lean to the right, but that doesn't mean they don't provide good service (or as best the economy will permit) to clients of all political stripes, the argument goes.

And professors should be assumed to have the same professionalism.

A new study, however, challenges that assumption -- at least in the field of social psychology. The study isn't due to be published until next month (in Perspectives on Psychological Science), and the authors and others are noting limitations to the study. But its findings of bias by social psychologists (even if just a decent-sized minority of them) are already getting considerable buzz in conservative circles. Just over 37 percent of those surveyed said that, given equally qualified candidates for a job, they would support the hiring of a liberal candidate over a conservative candidate. Smaller percentages agreed that a "conservative perspective" would negatively influence their odds of supporting a paper for inclusion in a journal or a proposal for a grant. (The final version of the paper is not yet available, but an early version may be found on the website of the Social Science Research Network.)

To some on the right, such findings are hardly surprising. But to the authors, who expected to find lopsided political leanings, but not bias, the results were not what they expected.

"The questions were pretty blatant. We didn't expect people would give those answers," said Yoel Inbar, a co-author, who is a visiting assistant professor at the Wharton School of the University of Pennsylvania, and an assistant professor of social psychology at Tilburg University, in the Netherlands.

He said that the findings should concern academics. Of the bias he and a co-author found, he said, "I don't think it's O.K."

Discussion of faculty politics extends well beyond social psychology, and humanities professors are frequently accused of being "tenured radicals" (a label some wear with pride). But social psychology has had an intense debate over the issue in the last year.

At the 2011 meeting of the Society for Personality and Social Psychology, Jonathan Haidt of the University of Virginia polled the audience of some 1,000 in a convention center ballroom to ask how many were liberals (the vast majority of hands went up), how many were centrists or libertarians (he counted a couple dozen or so), and how many were conservatives (three hands went up). In his talk, he said that the conference reflected "a statistically impossible lack of diversity,” in a country where 40 percent of Americans are conservative and only 20 percent are liberal. He said he worried about the discipline becoming a "tribal-moral community" in ways that hurt the field's credibility.

That speech prompted the research that is about to be published. Members of a social psychologists' e-mail list were surveyed twice. (The group is not limited to American social scientists or faculty members, but about 90 percent are academics, including grad students, and more than 80 percent are Americans.) Not surprisingly, the overwhelming majority of those surveyed identified as liberal on social, foreign and economic policy, with the strongest conservative presence on economic policy. Only 6 percent described themselves as conservative over all.

The questions on willingness to discriminate against conservatives were asked in two ways: what the respondents thought they would do, and what they thought their colleagues would do. The pool included conservatives (who presumably aren't discriminating against conservatives) so the liberal response rates may be a bit higher, Inbar said.

The percentages below reflect those who gave a score of 4 or higher on a 7-point scale on how likely they would be to do something (with 4 being "somewhat" likely).

Percentages of Social Psychologists Who Would Be Biased in Various Ways

The paper notes surveys and statements by conservatives in the field saying that they are reluctant to speak out and says that "they are right to do so," given the numbers of individuals who indicate they might be biased or that their colleagues might be biased in various ways.

Inbar said that he has no idea if other fields would have similar results. And he stressed that the questions were hypothetical; the survey did not ask participants if they had actually done these things.

He said that the study also collected free responses from participants, and that conservative responses were consistent with the idea that there is bias out there. "The responses included really egregious stuff, people being belittled by their advisers publicly for voting Republican."

Neil Gross, a professor of sociology at the University of British Columbia, urged caution about the results. Gross has written extensively on faculty political issues. He is the co-author of a 2007 report that found that while professors may lean left, they do so less than is imagined and less uniformly across institution type than is imagined.

Gross said it was important to remember that the percentages saying they would discriminate in various ways are answering yes to a relatively low bar of "somewhat." He also said that the numbers would have been "more meaningful" if they had asked about actual behavior by respondents in the last year, not the more general question of whether they might do these things.

At the same time, he said that the numbers "are higher than I would have expected." One theory Gross has is that the questions are "picking up general political animosity as much as anything else."

If you are wondering about the political leanings of the social psychologists who conducted the study, they are on the left. Inbar said he describes himself as "a pretty doctrinaire liberal," who volunteered for the Obama campaign in 2008 and who votes Democrat. His co-author, Joris Lammers of Tilburg, is to Inbar's left, he said.

What most impressed him about the issues raised by the study, Inbar said, is the need to think about "basic fairness."