I don't believe the judge just forgets that information exists. I believe the judge is well-trained enough to know what is and isn't relevant, per the law and the framework of the Constitution, in trying a case and I personally believe that most of them are able to keep that separate.
We'll just have to agree to disagree here.
Fair enough. On the whole I think our judicial system is a relic from before the creation of universal education. Without the benefit of anything resembling scientific study, I feel too much info is withheld from jurors. A jury today is no longer composed of 12 rubes gathered at the local barbershop.