Projection is similar to self confirmation however with self confirmation you're working on a theory, gathering data, where as with projection you just already know. It's just assumed, everybody but you is everything you hate about yourself and everybody knows it. Where as every single ego invested person is within some level of self confirmation, projection is generally only for the crazier amongst you, about one third of you. It isn't always you projecting qualities of yourself, there are many forms of projection. It seems to have become a very normalized label, I know I'm projecting, I'm doing that perfectly normal thing that borders on delusional hallucination.
The mechanism is generally seeing something in yourself that it has labeled unacceptable, your type of mind is now given the semi-conscious trauma response option to flag it as external rather than internal, error correction does not wish for this self model. Sometimes it is because your own semi-conscious block think will not allow for two states you deem contradictory, such as sometimes you're jealous of people but you also admire them. If you feel something, it's because the world makes you feel something, that'll work that's all you need.
Error correction now has a very complex system of ignore and insert. All the time, mismatch, mismatch, mismatch, you know what to do in these moments to reduce error, install discarded self model.
False Consensus Projection
False Consensus Projection: Foreword by Kit Carruthers