But we can localize it that precisely, and cheaply. In that particular experiment, they found that the areas of the brain that are commonly associated with raw visual input activates precisely whenever an image appears, subliminal or not. Then a large, delayed negative wave reliably appears in the frontal lobe only when the patient affirms that they saw the image. It's using objective methods to confirm the subjective.

These sorts of experiments are helping with making prognoses of whether a patient recovering from a coma will remain in a vegetative state, or if they'll regain consciousness in time.