Control Group Or Disability?

[paigetheoracle]

On the obesity thread I mentioned using wheelchair users as controls, to exclude lack of exercise as a cause of weight gain. Could the blind, deaf and other disabled people be used to test out theories, simply because of their sensory/ physical activity lack and has this already been tried? (For instance I remember that someone operated on to restore sight to them, which they hadn't had since birth, were discovered (contrary to expectation) still to be confused by vision, proving sight wasn't just a matter of physically repairing the mechanism but a perception/ processing problem too).