Seeing is not always believing

For many of us sight is the sense we use most to understand the world. Colour, light, shape and distance all inform us of the environment surrounding us. It may then come as a surprise to you to learn that what you see is not always what is actually there. 

Our eyes are the tools with which we collect information about our world but it is the brain that decides what we are looking at. Visual cues such as patterns, shadows and movement are fed to our brains so we can make choices as to what response we may take to this outside influence. Is this a threat? Is it a friend? Will it harm us or help us?

Fast fact: One third of our brain’s cortex is used for vision, more than for any other of our senses.

The eyes send an incredible amount of information to the brain. Add that information to the signals being sent from our others senses and the brain can very easily become overwhelmed trying to make sense of the outside world. To simplify the information the brain is receiving it creates shortcuts to help in making a quick decision as to what is in front of us. 

Optical illusions are a great example of how our brain’s trick us into believing we see something that isn’t really there. How these tricks work, however, has created as many theories as there are illusions!

One theory suggested by researchers is that to compensate for the amount of time between when something happens and when we are able to perceive it the brain predicts what it thinks is about to unfold. These predictions are based on what the brain has learnt from previous experience. And when that prediction does not match the reality we see the ‘illusion’ the brain has presented us with.

Illusions that show an inanimate object in motion have inspired another theory. In these cases some scientists suggest it is the rapid movement our eyes make (saccades) that cause a still picture to appear to be moving. In most cases the brain smooths out saccades, making them imperceptible to us, but in rare situations it does not or cannot. In these cases a picture may appear to be moving.

Who is that?

Have you ever seen a ‘shocked’ face when looking at an electrical outlet or a happy face when two sunny-side-up eggs fry in a pan with a slice of bacon? That’s pareidolia (Parr-i-Doh-lee-ah), a simple trick your brain is playing on you.

Since the moment we are born we are on the lookout for human faces. A human face represents food and shelter to us, especially when we are babies. Recognizing other human beings is so important to our survival our brains are constantly identifying faces where there aren’t any.

Article originally published in Brainspace Magazine Winter 2017/18

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