I was thinking that experience and background do not effect one's
preconception because preconception is when you know nothing about it.
Is there anymore reason to support this?

Narfiaska,

I'd say just the opposite...  Preconception is when you DO know (or
think you know) something about "it" ("it" being whatever) - however
wrong or misguided what you think you know actually is.  If you truly
know nothing about "it", then you can have no opinion, no prejudice,
no preconception.

Then there is the problem of those who continue in their
preconceptions, regardless of evidence to the contrary - try looking
up "belief perseverance", and especially the work of C.A. Anderson. 
I'm stuck for time, otherwise I'd have a go at a full answer for you. 
Good luck,  r2l