I think this is a psychologist issue, not a liberal/conservative issue. WND is one of the most biased sources available on the web. If you look up the actual survey, it's not quiet the same as is portrayed on WND, as most of the WND article is a conservative editorial. If you do a little more research on the study itself, the most reasonable conclusion is, as I expected, a numbers game.
"conservatives represent a distinct minority on college and university campuses. A 2007 report by sociologists Neil Gross and Solon Simmons found that 80 percent of psychology professors at elite and non-elite universities are Democrats. Other studies reveal that 5 percent to 7 percent of faculty openly identify as Republicans. By contrast, about 20 percent of the general population are liberal and 40 percent are conservative.
Mr. Inbar and Mr. Lammers found that conservatives fear that revealing their political identity will have negative consequences. This is why New York University-based psychologist Jonathan Haidt, a self-described centrist, has compared the experience of being a conservative graduate student to being a closeted gay student in the 1980s.
In 2011, Mr. Haidt addressed this very issue at a meeting of the Society for Personality and Social Psychology — the same group that Mr. Inbar and Mr. Lammer surveyed. Mr. Haidt’s talk, “The Bright Future of Post-Partisan Social Psychology,” caused a stir. The professor, whose new book “The Righteous Mind” examines the moral roots of our political positions, asked the nearly 1,000 academics and students in the room to raise their hands if they were liberals. Nearly 80 percent of the hands went up. When he asked whether there were any conservatives in the house, just three hands — 0.3 percent — went up.
This is “a statistically impossible lack of diversity,” Mr. Haidt said."
There are so many more liberals in the field of psychology, that there is naturally a group response of the vast majority of the field. Liberals tend to vote for liberals, conservatives tend to vote for and prefer conservatives. It's not evidence that liberals are more exclusive or bigoted than conservatives. It's evidence that most psychologist are liberal.