I don’t know if reality has a liberal bias, but I can think of one factor that relates to liberalism and the ability to assess reality. One study I’ve seen showed that liberals were on average less susceptible to confirmation bias than conservatives. Maybe it is unsurprising that conservatives wouldn’t be attracted to a field such as psychological research (or science in general) which seeks to avoid confirmation bias.
This might relate as well to the correlation of liberalism and ‘opennesss to experience’. It is obvious that aspects of ‘openness’ are directly oppositional to confirmation bias. To be low in ‘openness’ would mean to seek out the familiar and known, and as such would lead one to want to confirm what one already knows/assumes. It’s because of ‘openness’ that liberals enjoy discovering something new. A strongly liberal person finds pleasure in this and so discovering something new, even if it disproves former assumptions, is still seen as a good thing from a liberal perspective of ‘openness’. The liberal-minded person will even intentionally seek out the unexpected simply for the excitement of being surprised.
I think there is danger in seeing conservatives and liberals as neutral categories in all ways. For example, research shows conservatives have a better ability at focusing by excluding distractions while liberals are hyper-aware of their environment (and the people around them, i.e., empathetic awareness), and so it would follow that conservatives are going to be overrepresented in fields requiring high degrees of focus (I’m perfectly fine that most surgeons are probably conservatives; heck, give me the most conservative surgeon there is if he’ll save my life with his hyper-focused conservative mindset). Does this mean liberals entirely lack the ability to focus? Of course not. But it would be silly to criticize as anti-liberal fields requiring focus. It’s just a fact that conservatives are better at this just as it’s a fact that liberals are better at ‘openness’.
It’s not that the field of psychology necessarily has an anti-conservative bias, except to the degree that liberal psychologists have biases as individuals. Moreso, I suspect it is simply that the average conservative has an anti-psychology bias. You could possibly attract some conservatives who are moderate in their conservative predisposition, but it’s unlikely that strongly conservative people will ever want to be involved in psychology.
What might be interesting is to consider another aspect. Maybe psychology does have a liberal bias in one sense. Maybe thinking psychologically correlates to thinking liberally, the two either having the same source or simply closely corresponding in style. Maybe teaching conservatives to think psychologically would be equivalent to indoctrinating them into liberal thinking. It’s possible that psychological research couldn’t function (effectively? objectively?) if as a field it became dominated by conservatives. What if psychology itself is inherently anti-conservative?
This is similar to cities having disproportionate number of liberals. What if cities are simply liberally biased by their very structure? Maybe it would be impossible to build a city that wasn’t liberally biased, except in the case of totalitarian oppression that forces anti-liberalism onto a population. Liberals love new experiences and love diversity of culture, the very things that cities embody. What good would it do to try to attract conservatives to cities just to make cities more ideologically balanced? If conservatives choose to move to cities less than liberals, that doesn’t mean that there is any prejudice keeping conservatives from moving to cities. Affirmative action for conservatives probably wouldn’t make cities better places.
Anyway, would it even work? Research shows that children who grow up with cultural diversity tend to become adults who are more socially liberal. You could bring a conservative into a city, but then their kids would just more likely become liberals or at least more liberal than their parents. Similarly, you could force more conservatives into the psychology fields, but this just might change these conservatives toward liberalism. This relates to education overall. What if educating people inevitably makes them more liberal in the way that opening people to diverse cultures tends to do?