Friday, 16 May 2014

Window ghost turns red

 Sea wavesRegular readers may recall a window ghost I saw recently (see here). It is a fairly frequent experience which happens like this: I am inside a particular building and approaching one specific window, sideways on, when I get a peripheral vision glimpse of a figure at the window. If I get closer and/or turn to look straight at the window, there is invariably no one there.

I concluded, unsurprisingly, that it was a peripheral vision misperception. There was a remaining mystery, however. Just exactly WHAT was I misperceiving? I decided it must be a wall that partially obscured the window as I approached it. But it turns out that this was wrong! The clue was that the ghost suddenly appeared bright red, instead of its usual shadowy grey.

It turned out that someone had left a bright red object, the same hue, next to, but not overlapping, the window where the ghost appears. There are always objects in the same position but usually they are not brightly coloured. So, it appears that my peripheral vision had made an object next to the window look as though it partially covered it. Or to be precise, it looked like a shadowy figure outside the window.

Peripheral vision has, of course, poor resolution compared to central vision. But I think there is more to it. The low lighting conditions, that are apparently required for this ghost to appear, no doubt contribute. But there is also the fact that I'm short sighted. Though I see the ghost when I'm wearing my glasses, it is in peripheral vision which is an area not covered by my glasses! So the blurriness of my uncorrected vision is, I suspect, also important. Someone else in the exactly same location may not see the ghost at all!

None of this has anything to do with the photo (above right) which shows the sea. But just how big are those waves? They could be anything from a slight surf to huge rollers. This illustrates the difficulty of judging the scale of objects in anomalous photographs. What is needed is something of known size, visible in the photo, to get some idea of the scale. That small white object bottom right is a Herring Gull. Its typical length is around 65 cm and it is flying low over the sea. So those waves are distant and quite big!

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