Ever heard of the Implicit Association Test (IAT)?  It’s a kind of test devised to tell ourselves things about ourselves that we might not know.  Like giving ourselves an X-Ray.  From Project Implicit: “It is well known that people don’t always ’speak their minds’, and it is suspected that people don’t always ‘know their minds’. Understanding such divergences is important to scientific psychology.”  Which is why the IAT was developed.

You can take a whole variety of IATs at this site, like the Religion IAT, or the Gender/Career IAT.  Or you can take the Presidential IAT, to see which candidate you really prefer.  Even if you think you know whom you prefer.