Tuesday, 4 April 2017

No glasses, no ghosts?

Sun behind treeRegular readers will be aware that I notice misperceptions frequently. Such misperceptions sometimes take the form of ghostly figures or other anomalous phenomena. However, I've noted that I don't usually notice misperceptions when not wearing my glasses (I'm short-sighted). Given that misperceptions usually happen when an object is not seen well, this appears paradoxical. I suspect that, when not wearing glasses, I don't look at things too closely - I'm usually only concerned with not bumping into anything.

There was one unusual incident once where I had an obvious misperception while wearing no glasses - reported here. Interestingly, the misperception was IN focus! It suggests that my visual memory holds images that are IN focus and does visual substitutions accordingly. But that does also suggest that visual substitution seen while wearing no glasses should stand out. So why is that the only example I've noticed?

Recently, I decided to do an experiment. I went outside for a walk wearing no glasses, something I never do normally. I looked around a lot to see if there were any misperceptions. There were not. I could easily see well enough to get around without problem though everything was fuzzy and out of focus. I saw nothing unusual and nothing in focus. Of course, there is a problem with this method. If you deliberately look for misperception you tend not to notice it.

This clearly implies that though perception is essentially an unconscious process, there is a conscious element to it too. Such priming is well-known in neuroscience. It means that if you deliberately look for a ghost, one caused by misperception at least, you will almost certainly not see it. It is also the reason why once a misperceived object has been seen for what it really is, it is not usually misperceived again. I'll need to think of some different way of doing my 'not wearing glasses' experiment. Experiments involving perception are tricky! But the evidence so far certainly suggests misperception is rarely noticed when not wearing glasses. I'd be interested to hear from anyone who has seen a ghost while not wearing glasses that they normally wear all the time.

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