Wednesday, 26 August 2015

Tall thin green ghost

White streaksI became aware of a tall person standing behind me recently. I was outside, in daylight, with rain falling and a strong breeze blowing. The person was in my peripheral vision. I turned slowly, to look properly at them, only to discover there was no one there. So, a ghost then!

I quickly realised that what I was actually seeing was a tall bush, with a good covering of leaves. So it was a misperception ghost. The bush was tall and thin, its dimensions closely resembling those of a tall, thin person. It was, of course, overwhelmingly green which is not typical of a human figure. However, the colour was not so obvious in my initial view. Peripheral vision tends to look monochrome.

So, a typical peripheral vision misperception ghost sighting. Except that I wasn't wearing my glasses. I have quite pronounced short sightedness (myopia) and rarely go outside without my glasses on. This sighting contradicts an observation I made last year (see here). I had noted that I seldom, if ever, notice myself misperceiving when not wearing glasses. This latest observation directly contradicts that idea. So what's going on?

I had sacculated that objects seen as ghosts in normal vision were too fuzzy in myopic vision to be misperceived as human figures. This idea may still be true. What I failed to note was that some objects NOT misperceived as ghosts in normal vision may become fuzzy enough, in myopic vision, to be seen as human figures. In other words, myopia doesn't stop misperception, it simply shifts the distance (from the witness) of objects that might be affected.

So why do I not almost never notice misperception when not wearing glasses? It is probable that the range of distances (from me) over which objects may be misperceived is quite narrow when I'm not wearing glasses. It would require some experiments to determine this for sure. What looks certain is that myopia, and presumably hyperopia, can have a profound effect on misperception. It is clearly important to know if witnesses have either of these conditions and whether they were wearing corrective lenses when they had their anomalous experiences.

The motion of the bush in this observation was, I think, an important contributory factor to its being misperceived. Obviously, significant movement is more typical of human figures than bushes so it would have added to the impression of a ghost. Also, the bush was isolated from nearby vegetation. Taken together, the shape, dimensions, isolation and movement of the bush all gave it a distinctly human look when seen in peripheral vision.

PS: And the photo? More examples of white streaks - see yesterday.

No comments:

Post a Comment