Perception vs Reality

Perception is not Reality. Reality is Reality, and Reality is too complex for mere mortals to perceive in its entirety. What we perceive is just a model of Reality. Effective models reflect what is important about Reality, and what is important depends on observer and the observer's context.

The models we use organize and simplify what we perceive about Reality, and we use these models to make decisions. Good models (can) lead to good decisions. A model is a lens through which we view Reality. When Reality changes in a significant way, the view we see through this lens changes, and this allows us to respond in an appropriate way.

Note the use of the word 'significant'. Reality is constantly changing in ways we can't hope to comprehend. Your are slightly older now than you were when you started reading this. That is an example of how swiftly and constantly Reality changes. But is your increased age significant? No! So your model of Reality doesn't take this slight aging into account. Reality changed, but your view of Reality did not.

Someone walking into the room while you are reading this may or may not be significant. If you are currently alone, the entrance of someone else probably warrants your attention. But if you're in a crowded public space (say, a library) where people are constantly coming and going, the arrival of another person makes no significant difference; it doesn't affect your view of Reality. Unless...

Unless there's something 'different' about that person. We know, in reality, EVERY person is unique, and thus every person is different. But not every difference is important in your view of the current state of the world around you. And what is 'important' is contextual and subjective.
Contextual means it depends on other things. If you're in a public library, a stranger entering the room is no big deal. If you are at home 'alone' at night, a stranger entering the room unannounced is a VERY big deal.

Even in the library example, context matters. In the segregated southern U.S. of generations past, or in the apartheid South Africa, the arrival of a black person in a public library would have been very significant, whereas today it would probably be not. The context has changed.

Importance is also subjective. Is the 'sexual preference' of the people around you (or the people around your family members) important? Some would say yes, it's very important. Others would say it's not important at all. So people of varying opinions co-exist simultaneously. It's not the context that that causes too models to assign different importance to the same fact; the difference is subjective.

So we base our judgements on models of reality, and these models reflect that we feel is important about Reality. The key thing to remember is that the models are subjective, and are NOT Reality itself. Most of the time we behave as if the model IS Reality, because that's what the model is for: the model is the view of reality on which we base our behavior. If the model is a good one, the judgments we make based on it result in appropriate responses to Reality, and we benefit.