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The typical blindsight subject has one half-field of INTACT vision, with which he can negotiate the world, etc. There is no way (of which I am aware) of deciding whether a visual dream emanates from the intact or the blind hemifield. It would be important to study patients with total blindsight over the entire field due to bilateral visual cortical damage. Such patients are very rare.

In studying one blindsight patient, we did have evidence of internal visual generation, in one sense. This was a subject who had vivid after-images of the stimuli in the blind field of which he was unaware. When we presented him with a red stimuli to one eye and a green stimulus to the other eye, which in normal subjects generates a “cortical yellow” appearance, this subject reported a BLUE after-image, i.e., the complimentary colour of yellow. He did not see cortical yellow as such. The outcome could not be due to bleaching at the retinal level because that would have generated yellow. And so the after-image had to be generated brain activity induced by the initial stimuli. This is reported in my recent book, Blindsight (2009).