By systematic investigation do you mean a literature review? I hope so. Does such literature even exist, have you done any searches?

I have to take SSRIs to stay sane, but they blunt my emotions (which is usual) and kill my motivation. This has to affect my biases in some way. Then again depression would make me ridiculously biased. Nicotine and caffeine seem to make me overconfident, but help me to get things done.