Wednesday, 18 February 2015

How things vanish!

KingfisherCasually looking out of a train window recently I noticed two Magpies in a field. The furthest away turned so that it was no longer side on and promptly vanished from view. All I could see was green grass. The other bird was still plainly visible. Was the vanishing bird a ghost? Well, ordinary birds don't vanish in broad daylight. Or do they?

Regular readers will know that I go birding. Unfortunately, it can often take a while to locate a bird that others are already observing, even when given excellent directions. But here's the weird thing. I've often looked directly at a bush where everyone else could see the bird but I couldn't. All I could see was a bush! Then, suddenly, on yet another sweep of the bush, I see the bird. So where was it before? It was obviously there all the time because everyone else could see it.

I think this is a form of misperception that I've previously called an imperception. I think what happens is that when our brains do not see something well enough to distinguish what it is they simply visually substitute it with the surrounding background! So, we literally do not see an object even though it is in plain view. While I've noted imperceptions before, it hadn't occurred to me until the Magpie incident that our brains might be substituting 'background' in to make a poorly-seen object vanish altogether. The fact that the Magpie was apparently replaced by green grass was what led me to that conclusion.

And the photo? This is a real example of a bird I couldn't see at first, though others could, despite scanning the bush where it was perched many times. In this photo it looks rather obvious but it certainly wasn't at the time. The bird is, of course, the orange blob in the centre of the frame. It is a Kingfisher, hardly something you'd think anyone would miss.

It is clear that misperception can, in its imperception guise, explain some mysterious object disappearances. In the case of the Magpie, it vanished because the bird turned so that it covered a much smaller angle of view. The fact that I was on a moving train, getting further away from the bird all the time, no doubt helped. I'm still awaiting my first sighting of a human figure vanishing in this way. Most people seeing such a phenomenon would, very reasonably, report it as a ghost.

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