I was at a conference on 'brain research' last week in sunny Queenstown. There were some great talks, but I was particularly taken by one on the final morning by Jason Kerr, a kiwi now at Max Planck Institute in Germany. He was talking about the vision of rats, and described a very interesting series of experiments on working out just what a rat is seeing and how it uses this information. The experiments involved tracking what each eye was doing in different situations. It turns out that rats use their eyes in a very different way to humans. Rather than both eyes moving together (in phase) as a human usually does (left-eye moves left, right-eye also moves left) they can move either in phase or out of phase (left eye moves left, right-eye moves right) depending on the situation. While they have a decent amount of their field of view that is usually covered by both eyes, they don't appear to use stereo-vision, as such. Each eye might be looking at something different. But, maybe most interestingly, they have excellent coverage of the area above and behind their heads.
Jason showed a neat video of what happens when a rat in a large enclosure is presented with moving images in its field of view. Mess around with what a rat sees on the horizontal plane, and the rat doesn't bat an eyelid. But change anything above it, and the rat dives for cover. Why? It's one of those conclusions that are obvious in hindsight: What is the largest predator of rats? Birds of prey. Looking out for a threat from above seems to be the major role of the rat's eyes.
Anyway, so what has this got to do physics? Jason came up with a wonderful quote in his talk, relating to the power of a multi-disciplinary team for tackling a tricky problem. If I'd had a twitter account, I'd have tweeted it there and then. Instead, I hurriedly scribbled it down. Speaking to an audience primarily of biologists, he said:
Always hang out with physicists – they've already solved everything for you – they just don't know what to do with it yet.