Thursday, 26 January 2017

Something really strange

Misperception in tree Things don't move in still photos. In the picture (right) I saw something unusual in the tree. I noticed what looked to me like a human head just above the point where the main branches start spreading out from the trunk. It was, I quickly concluded, a photographic misperception. The head looked 'real', in the sense that it was, to me, a wooden statue rather than an actual living person. But then I noticed something really strange.

As I gradually zoomed in on the 'head' it suddenly 'moved'! From a distant view the head was facing me but then, as I gradually zoomed in, it was suddenly sideways on, looking to my right. If I zoomed out, the head got smaller but continued to be sideways on. And if I zoomed in a lot the head disappeared altogether to be replaced by the tangle of branches it really is. If I wait for a while, without seeing the photo, I can repeat the whole sequence again starting with the head once again facing towards me from a distant view. The head looked to be the same one in both versions.

So what's going on? I think that as the level of detail changes, the misperception flips from one head to another one. Misperception depends crucially on how well an object is seen. By zooming in I see the object better and the misperception alters. Eventually, having zoomed in a lot, I can see so much detail that the misperception vanishes altogether as I see the real objects.

The fact that the sideways misperception persists even when I zoom out is not unexpected. Once a misperception is 'broken' (when you see what the object really is) you don't see it again. It appears that once the first 'face on' misperception is broken, I don't see it again. However, if I wait for a while I can see the first one again as I have forgotten the sideways version. With a memory as bad as mine, that doesn't take long!

What makes this really interesting is that it may well happen with non-photographic misperceptions too. So, if a witness sees a tree as a human figure, it might appear to change if they approach it. This is important because it will hugely reinforce the idea that they are looking at an animate object rather than something inanimate. So such a 'changing' misperception is more likely to be reported as a ghost because it appears to be a moving figure. And an inanimate object can no longer be discounted as the source of a ghostly misperception just because it appears to change shape or move a little.

I have just noticed that if I stare at the photo for a while, I can see the head turn back and forth! It actually appears to turn rather than just flip from one state to another. I guess the 'turning' is my brain trying to make sense of something that should be impossible.

I had thought that a misperception could just 'break' and that was all. But now, it seems, a misperception can change into another misperception as well. It can even appear to move! While this change occurred by zooming on a photo I imagine a change in lighting could have a similar effect in a real life scene. Misperceptions are a whole lot more complex than I ever imagined.

PS: As usual with misperception, whether you see a 'head' in this photo will depend on the display you are using as well as how easily you notice misperceptions.

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