What you see is what you get
Looks can be deceiving: How your visual perception sometimes gets it wrong.
What you see – here, now, every day – is actually an approximation of reality made by your brain. In fact, if your brain wasn’t constantly working to make sense of the stimuli it receives from your eyes – if it simply faithfully reproduced everything your eyes saw – you’d perceive everything upside down. And that’s just for starters. Your visual world would be rather strange without the brain’s ability to interpret what you see. For instance, you wouldn’t perceive colours and your vision would end in a black zone at the edge of your visual field because your brain wouldn’t ‘fade-out’ the gaps. But this interaction between eyes and brain also manages to create some interesting visual illusions. Take a closer look at a few and tell us what you see.
Illusion #1 The Necker Cube
One of the simplest ways to determine WYSIWYG is the Necker Cube – an ambiguous line drawing of a cube.Take a look at the image below. If you’re like most of us, the orientation of the cube will keep changing as your brain tries to make sense of what it’s seeing. Essentially, your brain has developed two equally plausible hypotheses of what you’re seeing and flips back and forth between them while it tries to decide which one is more correct.
- You’ll also probably notice your eyes will choose to interpret each part to make the whole consistent.
- Most people see the lower-left face as being in front most of the time, probably because we’re used to viewing objects from above more than from below (so our brain prefers this orientation).
- The Necker cube is sometimes used to test computer models of human vision to see if they can arrive at consistent interpretations of the image the same way humans do.
Illusion #2 Concentric Objects
Keep your eyes fixed at the centre of picture below. Start to move your head backwards and forwards towards the screen.
Do the rings seem to be rotating in opposite directions? This effect occurs because your eyes have trouble refocusing and adjusting when you change proximity to the image.
Illusion #3 The Koffka Rings Illusion
Take a look at these three images and tell me… Is the ring the same shade of grey in all images? If you’re like most people, you probably answered, ‘No’… and you’d be wrong.
While the first grey ring looks uniform on the light/dark background, but when the halves are split the colours are quite different. The bottom image splits the halves vertically, giving you the impression of transparency.
Even though the half rings are set against exactly the same backgrounds, you’ll notice their appearance depends on the overall spatial configuration.
Illusion #4 Left/Right Brain Conflict
But what happens if your brain is required to interpret conflicting data simultaneously? The following visual illusion highlights this in a fun way.
Did you have trouble working out what you were supposed to do? Did your thoughts slow done while it tried to process the two conflicting inputs? That’s because your right brain was trying to say the colour while your left brain wanted to read the word!
Why it happens – two theories
Psychologist Richard Gregory (1970) argued that perception is a constructive process that relies on “top-down processing.” Because the information your senses gather is often ambiguous, your brain must use past experience or memory to make inferences about what you perceive. Gregory estimated about 90% of the information your eyes see is lost by the time it reaches your brain. He therefore posited all perception is mere hypothesis – we actively construct our perception of reality as we go. And any incorrect hypotheses will lead to perception errors, like those above.
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