To think something with full concentration I close my eyes. I believe many people also do it. It seemed to work and generates good thoughtful results. May be because with eyes closed brain is free to handle the billions of photons coming from eyes. In a noise-free room concentration should be even better. Is it the reason for getting the better result? Then if a learned man at his middle-age become blind (accidentally or purposely) then should he be able to perform better in solving problems, in psychology, in intelligent analysis etc.? Because his visual system is fully free always. We talk so much about photons, rods, cones, retinas, brain, perceptions etc. How all these matter for a blind person? How is their world?