Belief bias is when we make decisions not based on facts and evidence, but based on our feelings and beliefs. For example, let's say you hear a story about a dog that is mean and scary. Even though you have never seen the dog or heard it bark, you might have a belief that all dogs are mean and scary. This belief could stop you from wanting to go near the dog, even if the dog is actually friendly. Belief bias is when our beliefs change how we think and make decisions.