Best optical illusions and how they baffle us

In the words of Morpheus, “What is real? How do you define real? If real is what you can feel, smell, taste and see, then 'real' is simply electrical signals interpreted by your brain. And that is undeniably the truth as reality is perception. And if we tweak these impulses in the right way, one can play a few tricks on the brain. Optical illusions have been around for a while and here are a few of the best that will entertain you, amuse you and offer you an insight into how your brain works. And at any point if your eyes feel strained, do take a break… This is not a challenge!

The Illusion

The above image is not an animated GIF, and yet if you just are reading this text or not looking directly at it, the swirls in the image actually start moving. Concentrate on one of them, and the others that surround it start to move.

The Explanation

Still images that give the illusion of movement are an interesting psychological phenomenon that we have still not been able to unravel. Researchers are trying to understand why the brain responds in this fashion to certain patterns and colors. Experts at Chinese university of Hong Kong though have already deciphered the exact color combinations and patterns that induce the feeling of motion, but what happens inside our brain is still a mystery.

Here is an image of Van Gogh’s ‘Starry Night’ in similar repeated asymmetric patterns (RAP) created by the researchers. In this version the stars do move…

The Illusion

Also known as Pac-man illusion, this was created by Jeremy Hinton around 2005. Just concentrate on the small black cross at the center for about 15 to 20 seconds and you will see a green disc in place of the lilac disks running around. Concentrate harder and slowly you will see the 12 lilac disks fading away and the lone green disk dominating them.

The Explanation

The 12 lilac disks only appear and disappear for 0.1 second and this is continued in a cyclic fashion. While there is no actually movement a phenomenon called ‘Beta Movement’ in the brain creates the perception of a moving dot. The appearance of the green disk in place of the lilac is attributed to the adaption of the tired cones and rods of the retina as they replace the absent lilac with the opposite complimentary color green.

The Illusion

This one is pretty simple to try out. Just look at the spinning girl and tell which direction the figure is spinning in. Is it in clockwise or anti-clockwise direction?

The Explanation

No matter which way you got it, you are right. The spin in the figure will vary with perception and if you concentrate hard then you can change the direction the figure is spinning in. Experts believe that if the figure seems spinning in clockwise direction then the left side of your brain is currently more active and if the figure seems to be spinning in counter-clockwise direction, then it is the right hemisphere that is more active.

The Illusion

Look at the image and all you will see is a beautiful damsel. Now just walk a few feet away from the monitor and view the picture again. What do you see now? Is it the jealous boyfriend of the beautiful girl?

The Explanation

Created by Michael Sibbernsen and based on the work of Philippe G. Schyns and Aude Oliva from MIT, the image uses the perceptional differences that are caused by distance. The technique of this sort has been used in numerous images with various changes. Dubbed as ‘Hybrid Images’, they once again prove that even your eyes can deceive you.

The Illusion

Here is an image of a checker-board with blocks that alternate in shades of gray. Now you would assume by looking at the board that the gray of block A is a lot darker than the gray of Block that is labeled B. But both the blocks are of exact same shade of Gray. Yup, that does sound a bit unbelievable, but it is true. Both the blocks are of exactly identical color and it is just our eyes that deceive us.

The Explanation

This famous and astonishing illusion was developed by Edward Adelson, a professor in MIT Department of Brain and Cognitive Sciences. Adelson explained that the reason for this illusion is several fold. Firstly, our brain perceives colors in relative to those that surround it. This makes check A appear darker as it is surrounded by lighter checks and check B lighter, since it is surrounded by darker ones. The brain also makes a natural adjustment for shadows in order to perceive an objects natural color and since we are trained that checks have alternating colors and the ‘X-junctions’ formed by 4 checks is a boundary that signifies color change, we tend to assume that the checks are lighter or darker than they really are in the shadow.

The Illusion

This one is a bit crazy and not as ‘wow!’ as many of the other illusions we came across. But it does offer another unique insight into the way our brain functions. Concentrate on the white dot at the center of the video. Initially as the ring of colors is stationary, you will observe that each dot is changing colors. But as the ring of colored dots rotates, you will see that the dots suddenly have stopped changing color or do not flicker at the same rate anymore. But have the dots really stopped or slowed down when it comes to changing colors?

The Explanation

The reason offered by the creators of the Color-blinding wheel at Harvard University is that local detectors of the brain do not have much time in noting color changes because of the rotational movement of the ring of colors. They like to call it ‘change blindness’ and while we are no experts, we would like to call it ‘sensible prioritization’. The brain seems to pick up and chose data that is most important, relevant and useful rather than the useless. The test actually shows brain’s ability rather than a disability.

The Illusion

Okay, this one really blinded us after a while, so we suggest you do not stare at those vanishing dots too long. If you observe the intersections of the lines that form a grid pattern on the black surface, you will see that black dots seem to appear and everywhere else except the spot you are looking at. And once you shift your eyes on to a black spot it disappears. It seems like you can never catch the black dot…

The Explanation

This particular grid was created by E. Lingelbach in 1994 and is based on the famous Hermann grid. Scientists have explained this illusion with an optical process that is called Lateral Inhibition. The darker areas that surround the lighter interjections affect and are the reason for the illusion. But if we make the grid wavy and do not sue straight lines, the same result is not replicated. This has led to the questioning of the explanation offered. Still an open question…

The illusion

This one is pretty uncomplicated to observe. How do the lines in the image above seem? They are surely not parallel to one another and are bent, right? Wrong. All of them are straight and parallel to one another. Do not trust us? Just watch the same figure from the left or right side of your monitor with your eyes parallel to the screen. You will see the crooked lines straightened all of a sudden.

The Explanation

The illusion is caused by the alternating black and white blocks along with the separating grey lines and a change in the pattern of the bricks or the color of the separating lines ensures that the effect goes away. The exact reason as to why exactly this happens with the particular pattern and the color of the separating line is now known, but experts hypothesize that this occurs due to the limitation of neurons that make excitatory connections and Inhibitory neurons and the balancing act between both that enables us to differentiate between light and dark surfaces.

The Illusion

Here is another image that gives you the impression that it is animated as the spiral design here seems like it is spinning out and the little dots are flickering on and off as if you are at a carnival. Don’t get too lost in it though…

The Explanation

Much like the self-animated images, here is another place where we seem to perceive motion instill pictures. And while we are not certain on why this happens, it once again is attributed to the way in which the pattern is crafted so that it induces the feeling on motion.

The Illusion

Concentrate on the flickering dot at the center for about 10 to 20 seconds. Very soon you will find that the three yellow dots arranged at the ends of an imaginary equilateral triangle start to disappear. Sometimes it is just one of the dots and sometimes all of them vanish. They again reappear at random. This random vanishing and reappearance continues as long as you stare at the flickering dot at the center.

The Explanation

Motion Induced Blindness (MIB) is the phenomenon which causes this effect of disappearing yellow dots. Researchers believe that the brain ignores peripheral information at times as it concentrates elsewhere. Many have tried to explain why this happens and the debate as to what exactly causes this phenomenon is still very much on.

The brain is a very complex organ and while we have tried to provide with plausible explanations for each illusion, science is still unraveling the mysteries of the human brain. They are only the best possible and most logical reasons and in no way definitive. And the illusions only go to show the many useful tricks of the brain and not necessarily its weaknesses. Of course, how you view the abnormalities is again a matter of ‘Perception’. And perception is not always the truth…

 

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