John my friend,
Sorry to take so long ...
Focus in sensory systems likely follows rules similar to those in other systems. Get an early edge and exert inhibitory influences on competing systems. Gould perhaps describes it in the Burgess Shales, Microsoft tried to do it to Netscape, our prevailing models of ADHD and bipolar disorder resist mightily us rodents gnawing at their foundations. (I'll topple them yet by golly!)
Kauffman, sorry to mention the name -- GOT to try meeting him -- describes repetitive activity (stasis) and the absence of such (chaos) as a simple function of cross connections between decision units. ADHD folks may not have as much cross talk between competing psych adaptations. One is less able to suppress the others under changing stimulus conditions. I suspect comparable phenomena accompany CNS damage, certain bipolar phenomena, some anxiety disorders, and "immature" behavior. (See postings near the bottom!)
Forgive my zeal, but my gosh this rings true, at least for the past month or two.