(Image is a modified screenshot of Tom Hume’s weblog.)
Automatic attention allocation is a very pragmatic time-saving heuristic. It’s there because we can only see at the highest resolution right at the centre of our vision. That region is so tiny, it’s about the size of your thumbnail at arm’s length.
The rest is lower resolution, and at the periphery, you can barely see colour at all, and it’s only much good for picking up movement. If you don’t believe me, have a look when you’re next walking along the pavement in the same direction as the traffic. Look forwards, and notice the cars coming from behind in the corner of your vision. You can tell they’re there soon enough—but it takes a surprisingly long time before you can tell the colour.
Why not just have high resolution all over your eyes? Well, a couple of reasons. It’s a lot of information, firstly, and you don’t need it. It’s cheap to move your eyes, and the world doesn’t change that quickly. If it does change, then you look at it with your eyes and your head.
Second, you’d still need the low resolution periphery. It’s used to figure out where to look next. If something looks interesting, well, you check it out.
This makes me laugh when I see the peripheral awareness widgets in the corner of computer screens, in the taskbar or whatever. If they’re supposed to be meaningful without you looking at them, they shouldn’t be in colour because you can’t see that without looking directly at it. High contrast or black and white only please.
Anyway. Your attention moves about. If it goes somewhere – if it gets grabbed – your eyes follow.