You're more likely to believe the sentence "a chicken with four legs" vs. "a chicken with three legs". Both are actually wrong. Chickens have only two feet.
Moreover, you'll believe more that someone has blonde hair than brown hair when that person is from Europe, even though there are people from the west who are brunette.
This is all a product of cognitive ease which is produced by the illusion of familiarity, what feels good, what's easier, or even when you are in good mood.
When you are exposed as well to repeated words, you're more likely to remember and believe them to be true than other blurry words or words written in poor fonts.
Another example is when you don't know the answer to a question, you go by what feels familiar or what makes more sense to be true. You are not alone. Our brain is aversive to mental effort as much as possible, so we go by what feels easy and familiar; although what feels familiar can be nothing but real illusion.
How does this affect us?
In decision making, cognitive ease can be harmful especially when we always believe the first conclusion we come up with. Thus, it's important that we develop logic in analyzing problems, so that we can make better decisions. Yes, it might be hard as it requires you to think, but that's what the brain is designed for anyway.
If you are interested to know more about this topic, grab Daniel Kahneman's book called, "Thinking fast and slow." Not only you will learn the common thinking errors we make, but you'll also be in a great company.