Blind contour drawing
of three onions
Blind contour drawing is done by drawing the outline of the subject without looking at the paper. Many artists use blind contour drawing as an warm-up exercise because it reminds the hand how to draw what the eyes see.
If you think about what you're drawing too much, your logical brain tells you what the subject "should" look like, and that's where a good deal of bad drawing comes from.
We all have preconceived notions of how things look. Too see what I mean, make a very quick sketch of a tree. Then take a Dry Erase Maker to a window and trace around the contour of a real tree. The real tree outline will be much more complicated than yours. For one thing, you probably didn't draw any limbs coming straight at you in your sketch.
Drawing of three onions
blind contour drawing
Drawing a line coming at you (foreshortening) is one of the hardest things to draw accurately, and one of the best ways to draw that sort of line is to learn to "feel" it, and that's what blind contour drawing teaches you to do.
If you see a line leaning to the left, drawing the line blindly make your instincts remember how your hand needs to move in the same direction and at the same angle to draw it.
This "feel" for a line is very important. It leaps past logical thinking, which would like you get out a ruler and measure that line exactly, and lands you in a "senses only" world where the eyes see, the hand draws, and this coordination of your physical self becomes as graceful as two dancers who are each other's only world.
You do need your logical brain to draw accurately, but you just need it a little bit. You need it to glance at your paper and tell you where to start and end your lines and that's all. When you're really into a drawing, your eyes should be on your subject more than the paper. Just quick glances at the paper will be enough to keep the drawing on course.
After a good session of blind contour drawing, the rational part of your mind will be a gentle companion who offers infrequent advice instead of a dictator. And like anyone else newly free, you might miss the old boss. Don't worry though. You'll do much better without it.