False Consensus Effect
False concensus effect is an overestimation of how much other people share our beliefs and behaviors. For example, I know someone who is very health conscious when it comes to eating...she eats all sorts of grains, vegetables, etc., but stays away from fattening (but tasty!) foods. She is religious about eating healthy and truly believes that because she thinks it's important, everyone thinks it's important. This is a false consensus effect.