Signal to Noise and Pattern-Lock

The human mind creates patterns.  It's easy enough to see that to be true.  If you are in an office with a false ceiling, or spray on texture or something random like that, I want you to (wait for it) take a look at it for 30 seconds then come back here.
Okay, go.
Did you do it?  If not, then do it already!
Fine, I'll assume you did it.
Did you see the patterns?  Did the random dots form into wavy lines or faces or humongous single-cell organisms?  That is what our brains do, they try to build sense out of the random.
The question I have, though, is how much random can our brains take?  At what point does the noise become too much and it forces the little pattern makers in our heads to go cry in the corner?
Our world is full of inputs, little things that add clutter to our thoughts.  The background conversations at the office, the hum of the heating vents, the radio that you can just barely hear, the podcasts, twitters, emails, pages, text messages all come in at such a level that it becomes almost impossible to sort them into a coherent bundle.  The noise is too great and we go into pattern-lock.
I'm in pattern-lock right now.  It is not a case of 'not enough' ideas, it is more of a 'too many' ideas kind of thing.  I started my latest story, with a particular tale to tell.  But to explain that, there is backstory.  To understand the backstory, the universe rules must be known.  To understand the conflict between our main characters then something has to be shown for contrast.
All I know to do now is to pull the stories out of the jumble that I can and try to limit the noise getting into my system.  After I've done that (distilled the elements), perhaps I can find my way again.