Some new research is showing that the number of things humans can hold in our heads while solving problems is fairly small, three or four things at the most. Chunking makes it possible to remember more complex tasks:
It's difficult to measure the limits of processing capacity because most people automatically use problem solving skills to break down large complex problems into small, manageable "chunks." A baker, for example, will treat "cream butter, sugar and egg together" as a single chunk -- a single step in the process -- rather than thinking of each ingredient separately. Likewise she won't think, "break egg one into bowl, break egg two into bowl." She'll just think, "add all of the eggs."
I wonder how much the process of learning is just chunking task variables into larger and larger bits, building layers of abstraction the way a programmer might build an OO program.