Chris also shares on VanPatten:
So I asked Bill VanPatten for a metaphor and this is what I got:
Chris,
I use the metaphor of a grocery checkout. The cash register computer is the mind/brain. The bar codes on the product is the input. And the red light scanner is the input processor. The scanner can only read bar codes. it cannot read pictures, labels, rings on a can, signs, and so on. And the computer can only receive what the red scanner delivers to it as data. It cannot read the bar codes but instead the processed information processed by the scanner. Language acquisition is the same. Only input is useful for the input processor, not knowledge about language or practice. And the mind brain needs the processed input data in order to build a linguistic system. All components in both systems are dedicated to specific activities and act on only certain kinds of info. Does this help?
Bill