This looks interesting:
Implicit learning as an ability.
Kaufman SB, Deyoung CG, Gray JR, Jiménez L, Brown J, Mackintosh N.
Cognition. 2010 Sep;116(3):321-40. Epub 2010 Jun 22.
Looks like math is more heavily dependent upon explicit learning than language --- which makes sense, given that language is innate and math isn't (or not so much, at any rate).
Yet more evidence that the K-12, constructivist preference for tacit or implicit learning as opposed to direct, focused, conscious learning is a very bad idea when it comes to math.