The Science Behind Drawing the Figure Intuitively

When an artist is trying to learn to draw a figure in proportion and get the arms and the legs all the right size, it takes a certain amount of deliberate study, since there are all kinds of things working against him (for example, psychologically, we give more importance to heads and hands, so we tend to make them bigger; foreshortening in a lot of poses gives artists false cues about how limbs relate to each other). So there's a phase where a developing artist might spend a lot of time deliberately measuring out everything in the drawing to get it just right. 

But all of that academic study may still not give the artist sufficient grasp of proportions so that they won't still be a stumbling block. 

So I encourage artists to work a lot from FAST poses, usually 30 second poses, and to do a lot of them. Why? Because in 30 seconds, there's simply NO TIME to think about what you see and transfer that into something you're drawing on the page. Drawing fast COMPELS you to develop an intuitive understanding of the figure and it's parts as a single whole thing. With practice, it compacts that "conscious competence" into the subconscious part of the brain where it becomes a reliable, intuitive function. Not guessing.

Abraham Maslow identified this in his "Four Phases of Learning." To paraphrase, the first phase is not knowing anything ("unconscious incompetence") The second phase is knowing you have to learn ("conscious incompetence"). The third phase is learning and understanding, but only at a conscious, academic level ("conscious competence"). The fourth stage, which is where you've internalized the understanding to the point of intuitive understanding is called "unconscious competence." 

Unconscious competence can be as exotic as an athlete pulling an impossible play to win a big game or as ordinary as pulling into a busy traffic lane while talking to the kids in the back seat. Unconscious competence is writing out words without thinking of how to spell them, etc.