Four optical illusions will make you question what is right in front of you.
The mind-bogglers, shared by UK-based company Lenstore, are designed to trick you into seeing colour when there isn’t any, motion when things are staying still, and items that are right in front of you apparently disappearing.
Eye experts have also explained how each of the tricks of the eye work.
One shows a man who appears to be running – but actually it’s the lines around him that are.
Another shows a parrot that looks colourful, even though it’s in black and white.
DO YOU THINK THIS MAN IS RUNNING?
Watch as the black bars roll across the screen, is the man really running?
The answer is: No, he’s not.
Once you reach the end of the animation, it becomes clear that it was all just a trick of the eyes and mind. This is an example of an animation illusion.
Animation illusions were first discovered by Max Wertheimer in 1912 during an experiment involving lamps.
He found that light would jump from one lamp to the other when he turned them on and off in quick succession.
This type of illusion is the effect of the ‘Phi Phenomenon’, and can work by presenting a series of static images following quickly after each other.
The brain, because the images are presented in quick succession, then interprets this as meaning that the image is moving.
In this illusion, featuring the ‘running man’, the thin white lines which appear at the start of the animation are met with the thick black curtain as it pulls from the left to the right of the picture.
Because the brain can only process up to 12 images per second, and the image in this animation is constantly replaced within that time, the illusion of movement and continuity is created.
This process is known as the ‘persistence of vision’.
WHAT COLOUR DO YOU SEE WHEN THE IMAGE CHANGES?
Look into the parrot’s eye for 15 seconds. When the image turns black and white, what colours do you see?
The image remains black and white but a trick of the eye makes it appear as though the blue parts of the image are pink, and the pink parts of the image are blue.
That’s because the optical illusion is an example of a negative afterimage, which causes the colour you see to be inverted or reversed from the original.
An afterimage is a sort of optical illusion where the images keep appearing even after exposure to the original image has ended.
You have probably experienced this before if you’ve looked at something for a prolonged time, and you are still able to see it even after reverting your gaze somewhere else.
There are two main types of afterimage: positive and negative.
Positive afterimages are when the same colour as what you were originally looking at is still seen, even after the stimulus is gone – this may be due to the light going out or because you have closed your eyes.
You are still able to see the image in its original colours because some cells on the retina continue to send signals to the brain for a while after they have been stimulated.
In a negative afterimage, the colour you see may be inverted or reversed from the original picture. Just like the parrot seen above.
You are able to see an image with colours that are the reverse of how the image originally appeared. This is because the rods and cones, which are part of the retina, get overstimulated and become desensitised.
STARE AT THE CROSS… AND THE SPOTS BEGIN TO DISAPPEAR
If you follow the light grey spot around the circle in the video above for 30 seconds to a minute, you can notice that the other spot begins to turn green.
Another option for the illusion is to stare at the cross in the middle of the clip for thirty seconds to a minute, the spots making the circle begin to disappear.
They look as though they fade away following each turn the white spot goes around the circle.
This is called Troxler’s Fading, named after 19th century Swiss physician and philosopher Paul Troxler who found that the brain ignores visual scenes that don’t change and remain static.
Troxler discovered that focusing the eyes on a particular element in your visual field can make other elements, which are stationary, fade or disappear entirely.
The visual perception works with all different colours and variations of static and moving objects, as the unchanging stimulus away from the fixation point will fade away and disappear.
CAN YOU SEE THE CIRCLES TURNING?
If you stare into the centre of the different circles for a few seconds, it isn’t long before you can see the circles spinning slowly around
If you stare into the centre of the different circles for a few seconds, it isn’t long before you can see the circles spinning slowly.
The pink, blue, black and yellow design is a mind game called illusory motion, which is when the figure of an optical illusion (the circles in this case) appear to be moving even though they aren’t.
Visual scientists believe that involuntary eye movements could be the reason why the objects appear to be moving, but there is no solid explanation for why it does.
Some others have suggested that motion detectors in your visual cortex, the region of your brain that receives, integrates and processes visual information, gets confused by the changes in neurons which give the illusion of movement.