Steven Pinker -- How the Mind Works - Hampshire High Italian ...

The Mind's Eye | 257But now is the time to be vigilant about the homunculus. There is noproblem with the idea that some software demon or look-up algorithm orneural network accesses information from a scale model, as long as weare clear that it accesses the information directly: coordinates of a voxelin, contents of the voxel out. Just don't think about the look-up algorithmseeing the scale model. It's pitch black in there, and the looker-upperdoesn't have a lens or a retina or even a vantage point; it is anywhere andeverywhere. There is no projection, no perspective, no field of view, noocclusion. Indeed, the whole point of the scale model is to eliminatethese nuisances. If you want to think of a homunculus at all, imagineexploring a room-sized scale model of a city in the dark. You can wanderthrough it, coming at a building from any direction, palpating its exterioror sticking fingers through windows and doors to probe its insides. Whenyou grasp a building, its sides are always parallel, whether you are atarm's length or up close. Or think about feeling the shape of a small toyin your hands, or a candy in your mouth.But vision—even the 3-D, illusion-free vision that the brain works sohard to achieve—is nothing like that! At best, we have an abstract appreciationof the stable structure of the world around us; the immediate,resplendent sense of color and form that fills our awareness when oureyes are open is completely different.First, vision is not a theater in the round. We vividly experience onlywhat is in front of our eyes; the world beyond the perimeter of the visualfield and behind the head is known only in a vague, almost intellectualway. (I know there is a bookshelf behind me and a window in front of me,but I see only the window, not the bookshelf.) Worse, the eyes flit fromspot to spot several times a second, and outside the crosshairs of thefovea the view is surprisingly coarse. (Hold your hand a few inches fromyour line of sight; it is impossible to count the fingers.) I am not justreviewing the anatomy of the eyeball. One could imagine the brainassembling a collage out of the snapshots taken at each glimpse, like thepanoramic cameras that expose a frame of film, pan a precise amount,expose the adjacent stretch of film, and so on, yielding a seamless wideanglepicture. But the brain is not a panoramic camera. Laboratory studieshave shown that when people move their eyes or head, theyimmediately lose the graphic details of what they were looking at.Second, we don't have x-ray vision. We see surfaces, not volumes. Ifyou watch me put an object inside a box or behind a tree, you know it'sthere but don't see it there and cannot report its details. Once again, this