Focus of attention is a critical feature of living systems. Consider the eye. Minute detail is available at the center of vision. As you move away from that center detail rapidly drops off. Touch nerves are so concentrated in the fingers and tongue that braille dots spaced closely together can readily be distinguished, but three fingers touching ones back cannot be resolved when spaced half an inch apart.

Now concentrate on your bottom sitting in your chair, shift to your toes, now how warm it is, and finally an ambient sound in your immediate environment. This ability to focus your attention is a direct outgrowth of the presence of focus concentrations in your body.

But consider what we do in robotics. If we provide vision we have a display of say 460 columns by 350 rows, the American TV standard. Every one of those 161,000 pixels has the same 24 bits of information. Now the programmer has to decide what is important and what it means, a huge task. If the central 256 pixels were totally clear and rectangles extending outward looked increasingly like the blocks that hide faces on TV there would be fewer pixels to analyze and focus of attention by moving the eye would be mandatory. Consider these facts when you are designing your robotic hardware, because focus of attention lies at the heart of the "intelligence" in living things.

Another way: the frog only "sees" changes in its visual image. Even we still have some of this visual fatigue. Who hasn't stared at a contrasty black and white picture then looked up at the sky to see its negative projected against the blue.