Well I can say what happens with me, although as should be clear from this whole thread, other's experiences might be very different!
Visualising an image (of a memory, or an ideal) is a bit like tricking yourself into seeing something. There is no actual bike in your brain, just memories of what parts of a bike look like.
The trick is your brain putting those parts together and presenting that composite as 'a bike'. So i can understand how - some people - can 'see' what they think a bike looks like but then draw a mechanical mess.
Of course there are people with perfect recall, and others who design bikes for a living and so on. I'm really just describing how it could happen for some group of people.
That makes sense. So perhaps you could simplistically think of it like this then: the brain remembers things somehow, and when recalling, it runs that internal representation of that memory through some kind of a machinery that visually presents it to you? Only in some people that machinery actually doesn't produce visuals, but something else? (And I would seem to be one of those people).
Visualising an image (of a memory, or an ideal) is a bit like tricking yourself into seeing something. There is no actual bike in your brain, just memories of what parts of a bike look like.
The trick is your brain putting those parts together and presenting that composite as 'a bike'. So i can understand how - some people - can 'see' what they think a bike looks like but then draw a mechanical mess.
Of course there are people with perfect recall, and others who design bikes for a living and so on. I'm really just describing how it could happen for some group of people.