To thematize the blind spot of perception, or the impossibility of directly perceiving one’s own eye during vision, concerns aspects that do not belong to perception in the strict sense: we experience things directly; we do not perceive our perception of them, nor do we see the physiological processes that underlie perceptual activity. However detailed a physiological account of the hand may be, it tells us nothing of the meaning of a gesture, whose sense belongs instead to the phenomenological register. Similar considerations apply to the technological devices we use daily: their meaning for us is autonomous with respect to the hardware layer that supports them. Our relation to such devices is constituted by the interfaces we manipulate, not by the functioning, unknown to most, of the underlying mechanisms. Interface design in computing must be consistent with technological development, yet is also logically independent from it, because it answers to the bodily and spatial schemas of use.