Biased Evidence Gathering

Biased evidence gathering means you already believe something to be true, so you gather "evidence" that supports your belief, and you ignore and dismiss information that does not support your belief.

So if I don't want Bigfoot to be real, I will be dismissive toward any evidence of its existence, and say that it's "bunk".

If I'm objective, non-biased, and scientific, I won't be emotionally invested in whether Bigfoot is real or not, at least not very much, and my ego won't be a factor. I won't be annoyed or upset with evidence that someone wants to analyze, nor will I be annoyed with people who believe Bigfoot is real. I won't LIKE people "better" who don't think it's real, nor will I think they're "smarter". I might be annoyed with a person's behavior, the way they're acting, but it would have nothing to do with their belief either way.  

If a scientist (or non-scientist) BELIEVES IN a theory, point of view, or opinion, no matter how much due diligence and objective observation they THINK they're doing during information gathering and analysis, they are still operating under the influence of their BIAS, what they want to be true.

So if you want dogs to be cooler than cats, then you're going to list "reasons why" that's true, you're not going to be looking for reasons that cats are cooler, or that they're the same coolness.
If you want Asperger's syndrome to be a "boy-thing", then that's what you're going to try to prove.
If you want empathy to be a "girl-thing", then that's what you'll be trying to prove is true.

When we believe something is true before we gather information and evidence, we look only for the pieces of information that align with what we believe, and we ignore, even mentally bury information and facts that contradict our preference.