Strangers to Ourselves:
“Consciousness is the mere surface of our mind, and of this, as of the globe, we do not know the interior, but only the crust. ”
—Arthur Schopenhauer (1788–1860), German philosopher
Have you ever looked at a friend through a goldfish bowl? If not, try it out when you get the chance: you will find that your friend appears upside down. In itself, that is not too surprising. What is surprising, however, is that your own eyes bend light rather like a goldfish bowl does. That is to say, although the image of an object lands upright on your cornea, it does a vertical flip within your eye, and reaches your retina upside down. Nonetheless, you do not normally perceive your friends to be hanging by their feet from the ground above. There is consequently a contradiction between how things are in the world and how they are presented to your visual system. This contradiction is brought out even more clearly by the following remarkable fact: if people wear special goggles that invert their field of vision, they start to see the world the right way up again after a few days (Stratton, 1897). Somehow, regardless of how the world actually is, the visual system is bent on making vertical sense of it.
Findings like these carry a profound implication: our visual system does not simply reflect external reality but rather actively constructs it. Although this view seems bizarre at first sight, there is plenty of evidence to support it. Consider, for example, what happens when different parts of the occipital cortex (the outer layer of the brain towards the back of the head) are damaged. Several types of specific visual deficit then occur, many of an exceed