We don't see the things we visualize, we feel them.  As an example, look at this green square ? you see the color green with your eyes and you simultaneously feel/know/think the color. If you now close your eyes and try to imagine the color you get the exact same feeling but the sight is no longer in your field of view. Since the feeling is the same we trick ourselves that we actually see it. The practical lesson here is that if you do visualization, yoga, meditation or problem-solving using your inner vision, know that you are really looking for a feeling and if you try to find an actual sight you will just spin your wheels.