Sunday, December 07, 2003

Triple Take

To improve my fitness and to loosen up a bit of muscle tension, I've taken to swimming once a week. I usually swim at the UQ (University of Queensland) pool, and lately I've been swimming on Sundays in the later afternoon when the sun isn't so intense and things are quite pleasant.

Last Sunday I was riding down to the pool, which is about 20 minutes from my place. Most of the trip runs near the river, which lends a pleasant something to the surrounds, even if it isn't actually visible most of the way.

I was riding along a long flat stretch of road not far from the university when an interesting sight caught my eye. On the other side of the road about 50-100 meters ahead of me there was an older guy on the footpath.

He was standing side-on to me, leaning in towards some plants -- and there, projecting from his mouth, down and towards the plants was a big, continual spray of water, as if he was one of those water fountain statues, a plant-watering water-statue.

That image held place in my perception for, probably, a few tenths of a second, before being overthrown by the far more plausable notion that what I was seeing was a visual illusion, probably a result of the particular angle and distance I was viewing the scene from, rather than the sight being the University's latest research into genetically-engineered retirees.

The more realistic interpretation was that the water was coming from a hose was being held up by something that was actually further away than the man was, and that the nossle of the hose just happened to line up exactly with the guy's mouth. It was like one of those pictures which starts out looking like one thing then suddenly resolves itself into something else.

I had to laugh when I got a little closer and saw what was really going on. Neither of those perceptions was right, and I experienced a third shift of perspective. I had to laugh because I thought I'd seen -- with my second impression -- the truth behind the illusion, and as it turned out the first one was, in a certain sense, actually closer to the reality.

The water wasn't coming from some source behind him, it did originate from where his head was. At the same time, the water was coming from a hose. The answer? He was holding the hose in his mouth. It was a quite graphic illustration of the ambiguity our perception has to work with, and how interpretations that can seem so right can turn out to be so wrong.

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