I just want to reemphasize what @poisonedantidote said – confirmation bias is most often something that happens completely subconsciously. I think of it as the tendency to notice the times when something happens that supports a preconceived idea, and forget that it doesn’t happen the rest of the time.
My favorite example that I think happens to all of us at one time or another (or maybe that’s just a result of confirmation bias ;-)) is walking under a streetlight when it goes out. There was a time that I was convinced that it happened to me all the time, and irrationally (but not seriously) that maybe I had something to do with it. Of course, removed now, it wasn’t happening every night, and the nights it happened it happened once. It’s fairly certain that I walked under 99.999999% of the streetlights in my life and they didn’t go out or were out already. And it’s pretty certain that many other random people walked under other lights when they were going out. But I noticed when it happened because it meant something to me.