Research since the 1970s has consistently found that professors are more
liberal and
Democratic than the general population. A 2007
Zogby poll found that 58% of Americans thought that college professors' political bias was a "serious problem". This varied depending on the political views of those asked. 91% of "very conservative" adults agreed compared with 3% of liberals. {{Image frame|width=400|caption = Self-reported political views of U.S. academic faculty (% by year), according to the
HERI Faculty Survey reports 1990–2017 A nationwide study conducted every three years by the
Higher Education Research Institute (HERI) of
UCLA shows that from 1989 to 2014 professors identifying as liberal or far-left increasingly outnumbered those identifying as conservative or far-right. The shift from 2014 to 2017 was less extreme than prior years, with numbers standing at approximately 60% liberal/far-left, 28% moderate, and 12% conservative/far-right. According to Stephen Hayward, the fewer conservative professors results in fewer conservative students being mentored and supported to seek graduate level education, creating a "self-reinforcing" cycle. In 2012,
Tilburg University psychologists
Yoel Inbar and
Joris Lammers conducted anonymous random surveys of 800 members of the
Society for Personality and Social Psychology and found that 85% of respondents self-identified as liberal and 6% self-identified as conservative. Respondents that self-identified as either conservative or moderate were found to be significantly more reluctant to express their political views to their colleagues for fear of negative consequences, and were more likely to believe that their colleagues would actively discriminate against them on the basis of their political beliefs. In January 2015, a major literature review co-written by psychologists José L. Duarte, Jarret T. Crawford,
Jonathan Haidt, Lee Jussim,
Philip E. Tetlock and sociologist Charlotta Stern summarized numerous studies of how academic psychology has little ideological diversity, that the ratio of liberal-to-conservative or Democratic-to-Republican professors has dramatically increased since 1990, that the disparity is undermining the quality of research in psychology, and that the main causes of the lack of ideological diversity are self-selection, hostile climate, and discrimination. In September 2016, a replication and extension of the 2012 Inbar and Lammers study conducted by psychologists Nathan Honeycutt and Laura Freberg surveyed 618 faculty members of four
California State University campuses and confirmed the previous finding of a hostile climate towards conservative professors in academic psychology departments, but also extended their study to 76 other academic departments spanning agricultural, business, education, arts and letters, engineering, and science colleges and found that there are sizable percentages of professors willing to discriminate against conservative academics in every academic department that they surveyed. ==Student conservative groups, free speech, and hate speech==