Blind contour drawing: eyes on the model, pen never lifted, and the page does not show you the line while you are making it. That refusal is the practice, not a feature. When the timer ends the sheet appears. Then, if you want it, a second pass where looking is allowed, kept as its own dated sheet.
The blind pass
20:00
Eyes on the thing you are drawing. Do not lift the pen. Do not look down.
Hidden until the timer ends.
The two passes are kept as separate dated sheets. The page does not compare them, does not score likeness, and does not tell you which is better.
Sheets kept
The honest limit, stated first. Blind contour works and the explanation attached to it does not. There is no right brain to switch into: a study of 1,011 brains found lateralized networks and no left dominant or right dominant people. What happens is better described as suppressing the symbol: unable to see the page or correct, the hand stops drawing the sign for a hand and starts tracking an edge. The teacher who published the exercise in 1941 attached no brain to it and argued touch instead, and his text never uses the word. The brain framing sold millions of copies partly because it gave permission to people who believed they could not draw, which makes this a real benefit reached through a false mechanism. And no controlled trial of the exercise itself exists anywhere.