Dreams can be very vivid and detailed, and our brains seem to have little problems creating complete locations very accurately just from memory.

However, there are certain things that just don't work in dreams (at least in my dreams; though I know that lots of people have experienced the same). I'm talking about stuff like:

- light switches that don't work
- not being able to dial a telephone properly (I usually have to start over and over because I keep on misdialling)
- hands having the wrong amount of fingers
- letters jumping back and forth when you try to read something

They all make for great dream signs, so I don't mind. I just remember reading somewhere on this site, that our brains use schemata to create the dream reality (which makes complete sense to me), and these schemata are based on our waking life experiences. Now, when I use a light switch in waking life, the lights go on. One might expect, that it would be the same when dreaming – I mean, I EXPECT it to happen. Still, in my dreams it never works.

It's the same with my hands: even before I chose them as a dream sign, they looked strange in my dreams. So, it's not my expectations deforming my hands, it has to be something else.

My point is: if our brains are capable to build stunningly detailed dream realities from memory, places that we have been to, how come it fails at less complex stuff like light switches or the number of fingers? Any thoughts?