Because we are not psychic or omniscient, we cannot know each other directly. We build models of each other in our minds. When we say “I know Bob,” what we mean is that we have a model of Bob in our mind.
Sometimes the model is inaccurate. This can be a result of our biases, of deliberate deception, or of simple ignorance. But sometimes we do something that’s pretty weird. Sometimes we mentally associate a person with someone else’s model.
The idea of a person pretending to be someone else is straightforward. But a person can also pretend that someone else is someone else. We see this most obviously in dementia patients, who may sincerely believe that a person they are talking to is a different person, that their child is actually their long-dead parent, for instance.
People who do not have dementia can also do this, but they do it by halves. No non-demented person will ever think that their child is their parent, but they may think that their child is just like their parent. The mental model for one person can be associated with another person, a proxy persona.
This is different from stereotyping because stereotypes tend to be “default” personas that can be broken down and replaced by real information. But proxy personas are interactive. If you have associated me with a proxy persona, then you will interpret everything I say and do as if the proxy had said or done it. If I do something that contradicts your stereotype of me, then you will recognize that your stereotype is inaccurate. But if I do something that contradicts the proxy persona you have assigned me, you will think I am being deceptive or evasive.
“If [proxy] said what [person] just said, he would lying. Therefore [person] is lying.”
I suspect that this phenomenon is very common, but it is hard to recognize, because a person who is using a proxy persona will not give any explicit sign. They will treat their victim in a way that is subtly irrational or unfair, but not recognize that they are doing so, and perceive the victim as being unreasonable or dishonest if they object to the unfair treatment.
I suspect that many failures to communicate–both in public and private life–are due to people not actually talking to each other, but talking to proxy personas that the other parties are not even aware of. People think they’re talking to each other when they are really just talking to themselves.