How do we learn about the real, three-dimensional world? We've seen how certain agencies might map the layout of the skin. But how could we progress from that to learn about the world of space beyond the skin? One might ask why infants can't simply look around to see what's really going on. Unfortunately, the easy-sounding phrase simply look conceals too many hard problems. When you look at an object, some light from it shines into your eye and stimulates some sensors there. However, every motion of your body, head, or eye makes drastic changes to the image in your eye. How can we extract any useful information when everything changes so rapidly? Although it should be possible, in principle, to design a machine that could eventually learn to relate those motions to the resulting changes in the images, this would surely take a long time, and it appears that our brains have evolved with special mechanisms that help us compensate for motions of the body, head, and eye. This makes it easier for other agencies to learn to use visual information.
Later we'll discuss some other realms of thought in which we use analogies and metaphors to change our points of view. Perhaps those wonderful abilities evolved in similar ways, since recognizing that an object is the same when seen from different views is not so different from being able to imagine things that are not in view at all.
In any case, we really do not understand how the child learns to understand space. Perhaps we start by doing many small experiments that lead to our first, crude maps of the skin. Next we might start to correlate these with the motions of our eyes and limbs; two different actions that lead to similar sensations are likely to have passed through the same locations in space. A critical step would be developing some agents that represent a few places outside the skin. Once those places are established (the first ones might be near the infant's face), one could proceed to another stage: the assembly of an agency that represents a network of relationships, trajectories, and directions between those places. Once this is accomplished, the network could continue to extend to include new places and relationships.
However, this would be only the beginning. Long ago, psychologists like Freud and Piaget observed that children seem to recapitulate the history of astronomy: first they imagine the world as centered around themselves — and only later do they start to view themselves as moving within a stationary universe, in which the body is just like any other object. It takes several years to reach that stage, and even in their adolescent years, children are still improving their abilities to envision how things appear from other viewpoints.