Does this seem like a radical question to you? As radical as it once was to suggest the earth was round?
'Perceptions' are made two ways, naturally and artificially. Creatures with eyes have a nervous system etc. to make perceptions naturally.
Language is a second means of making perceptions, not all creatures have language like humans. Simply by 'believing' some thought-images are real, and you customize perceptions to suit you.
Of course you been doing so unwittingly/subliminally; no wonder you don't like,some of the results. You probably take this so much for granted you don't even believe this "radical" notion.

"Beware" of thought-created perceptions; they "can" be hazardous to your mental health.
..........Breeach Therapy.......... ( ass-backwards). I'm not discrediting therapy, I'm simply saying most are archaic, like blood-letting in early medical practice. I question the methodolgy.
Which is tinkering with "problematic" thoughts. Questioning, challenging, repairing, changing, replacing, etc. There's myrid such thoughts. What makes them "problematic"? Is there a common denominator? Yes, they are "believed". No matter how different from each other the different thoughts are, they are 'believed; and therein is the problem, as I see it.
We all know someone who is prejudiced but we are not (not with the same one). We know the prejudiced thought, it's in our 'head' as it is in theirs. But we don't react to or from it. Why? Becaue we don't "believe" it. We don't tinker with it nor try to get rid of it, etc. We simply do not believe it, rendering it harmless, to us.
( I came to this site, about February 2011 to learn and share about 'understanding believing' , (the process, not the content). I suggested collaboration, non forthcoming even to date, it seems I'm on my own; it's slower that way, it's now mid December.) Every reader 'believes'; what do 'you' know/understand about 'believing'?