Pelicans crossing

So, to continue the theme of blind people and road crossings, one of the things that my lecturer mentioned was that the push boxes at Pelican crossings, where you push a button to indicate that you wish to cross, have haptic 'displays' to supplement the visual and audible ones. Haptics is to do with touch, and what the displays consist of is a metal cone that rotates when it is safe to cross.

Yesterday I was looking for them, but all I could see was two yellow things that protrude underneath the box. I had the impression one of them was rotating, but I think, in retrospect that this was a hallucination. This evening, the sharp eyes of my daughter, Ruby, which are mounted a little lower than mine, found the rotating thing itself. She agreed that it was very cool.

What amazed me yesterday was that I had never before seen the former protuberances, which, while they are not huge, are not insignificant either. You will, I'm sure, notice them yourself now if you hadn't before. Having no idea that they were there, I had never seen them. It's possible, of course, that they are a new thing, but scarcely possible that they have changed or adapted every crossing button box within the last few days.

What it illustrates to me is that we actually build our worlds depending on what we expect to see. I don't mean that the thingies did not exist at all before I knew to look for them, but at least that they did not exist to me. So I didn't see them. This is not revolutionary thinking. From my layman's reading on the matter, it seems to be well accepted in cognitive science circles that we paste together brief and fragmentary perceptions into a seamless experience. In other words, the process of consciousness (for want of a better phrase) is a constructive one. We continually build our reality.

Ruby also continually builds her reality, and I think hers is quite different to mine, although luckily we share enjoyment in a lot of the same things, such as sushi, rock-climbing and practical jokes. I am often surprised at how intelligent she is (I asked her tonight whether she thought animals had language and she said 'yes' and I said how do they talk? "In movement" was her precocious and thought-provoking answer. She also made the throwaway comment "and rhinos think in smell" which blew me away!) But perceptually, she will often miss something that is right in front of her, leading typically to my impatience and, I suppose, mildly irritated thoughts along the lines of "come on, open your eyes, you're not even trying to even see it." I will pause at this point in the future and ask myself whether it's possible that it's a 'glue' issue, that her memory or conceptual experience just doesn't have enough in it to construct the world in a way that would include certain things. Sorry if that's a bit abstract.

Let me give a more concrete and easy example of the power of the brain to piece together incomplete data. Most people are aware that they have a blind-spot, an area on the retina which cannot receive visual information. It's due to the way that the optic nerve enters the eye, and would be a poor design, if someone had designed it, because it's quite close to the focal point. If you've not tested this before, try this. What's particularly interesting is that you don't 'see' a hole in your perception; there is no discontinuity. If the background colour is green, from which you 'lose' an object, you see an expanse of green, if it's yellow, yellow. If you don't believe me, try another example.

To give a more dynamic example of this, see this revolving dancer. She's sort of like the hollow mask experiment. Both are examples of sophisticated optical illusions. Actually optical illusions is not an accurate description of them; they are examples of where our sensory processes make assumptions, based on what they expect. I don't know whether this is learned or innate. I suspect it's largely hardwired into the optical processing areas of the brain, which are pretty large, it seems. The Buddhists, who have been studying human consciousness for thousands of years, and keeping records of their observations, separate seeing into the organ of sight (the eye, of course), visual consciousness and the space in which this happens. I don't really know what the latter refers to, but I think it's a tantalising glimpse of a potential area of scientific discovery.