Thursday, 6 October 2016

Ghostly leaf in focus to myopic witness!

Bird with out of focus background and foregroundI recently noticed something rather odd and completely unexpected. It was a white leaf which was not attached to a plant. Surprised, I looked more closely at the object and it quickly vanished. So, a ghost leaf then!

It became obvious that the sighting was a misperception. The object being misperceived was a patterned curtain illuminated from behind by the sun. The pattern did include some flowers in its design but they were stylized. The ghostly leaf, however, looked entirely natural.

Now here's the really strange bit. I am myopic (short-sighted) and did not have my glasses on at the time. Though the patterns in the curtain were fuzzy to me (I could not even recognise the stylized flowers), the 'leaf' was not - it was sharply in focus. In the past (here) I'd noted that I do not notice misperceptions when I'm not wearing glasses. Now it seems that is incorrect. I strongly suspect that seeing something in perfect focus (when it's at a distance where everything is out of focus), while not wearing glasses, is probably a sure sign that it is a misperception!

So how come I've never noticed this extraordinary effect before? Perhaps it is a rare effect. Or it could be because, when I'm not wearing my glasses, I don't look at things too closely - I'm usually only concerned with not bumping into anything. I think my visual memory holds images that are IN focus and does visual substitutions accordingly. This makes sense because I wear my glasses most of the time so I probably store all, or most, images in focus in my visual memory.

So, if a ghost witness is myopic and sees an apparition while not wearing glasses (while in bed, for instance), it would be interesting to know if the figure looked sharp or not. A sharp figure might well indicate a misperception. This might be a unique example of a myopic person seeing something in focus unaided, albeit an unreal object. Misperception just keeps springing surprises!

PS: The picture (above right) is just an illustration of a how a sharp object stands out against fuzzy background and foreground. The ghostly leaf stood out for that reason.

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