57. Invisible Statues

17 Mar

MISCONCEPTION: I can see things that don’t move. Like a statue.

TRUTH: It is impossible to see something that isn’t moving. If you can’t see it move, it’s invisible.

This works only because the eye works by detecting movement, and any old images are very quickly over-ridden. So how do we see statues?

The problem the eye faces is that it is designed with the detection of movement in mind. So it would struggle to see statues – unless they were moving. Now, the eye can’t move every still thing it sees, but it can make them appear to move. This works because of a kind of relativity. For example if you are running towards a pebble, you could say it looks like the pebble is moving towards you. This apparent movement means the eye can see it. Now say you look from left to right and there is a building in the middle. As you slowly turn clockwise and pass over the building with your gaze, it look like the building is moving in the opposite direction. So the eye can see the building.

Now, that last example shows that if you move the eye, something still such as a building will appear to move, making the eye detect it. This is exactly how we manage to see inanimate everyday – our eyes constantly twitch.These twitching movements of the eye are going on almost constantly without you knowing about it.

These twitches, or saccades as they are known, are tiny movements that are barely perceptible. They do cause some shake though, so your brain steps in and assists by just telling you, ‘There is no shaking going on here’ and as you may know, people tend to listen to their brain. In fact these movements are almost constant and involuntary, your eye is performing saccades right now, but you just don’t notice.

Saccades are the whole reason everyone (including most animals) can see statues and other very still things, they just make everything that isn’t moving, look like it’s moving. Be thankful.


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