  With regard to the continuity issue, as noted in §3, a position along these lines has been advocated by Dennett. If asked whether our typical visual fields are fully continuous, even when one of our eyes is closed, most of us are inclined to answer in the affirmative: when we look at (say) a white wall, we see an uninterrupted expanse of white.  In such cases we are certainly unable to detect a beachball-sized fuzzy dark expanse lying just to one side of the central axis of vision. But the physiology of the eye suggests there should be a ‘blind spot’ at that location, corresponding to the region of the retina occupied by the optic nerve which is devoid of light-sensitive cells. As for why we do not detect a blind region in our visual field, the standard – and on the face of it, plausible – answer is that our visual systems engage in some ‘perceptual interpolation’ or filling-in: our brains extrapolate from the stimuli reaching the light-sensitive cells in the region of the retina immediately surrounding the blind-spot, and fabricate experience to fill the relevant region of the visual field accordingly.