What is confirmation bias?
You don't search for the truth - you search for proof you were right.
We tend to look for, remember, and trust information that fits what we already believe, and we discount evidence that contradicts it.
Convinced a coworker dislikes you, you read every short reply as cold and skip the friendly ones.
You notice the hits and forget the misses that disagree with you.
Before deciding, go look for the strongest case against you - it's the evidence your brain hides.
You count the hits and forget the misses.
Learn the idea and practice English at the same time.