This is a lovely illusion – just look at the black dot and you will see grey as blue or green….

Does it work for you?


  1. I guess the addition of that grey and orange gives the blue we see (the actual color value)
    And the dot being black is probably irrelevant but just a sober color is probably better not to confuse our eyes more.
    I like it

  2. The black dot is just a focus point, so that you only see the orange box and grey bar with peripheral vision, I think.

  3. Looking at the video in full screen mode it works very well. So why does this work only in peripheral vision? The arrangement of rods and cones in the eye, or is it a processing effect?

  4. I tried to figure out by eye exactly what shade of blue it looks like, and I make it #00A0FF-ish (that’s 0, 160, 255). Now, the orange is #FF8000 (actually #FE7F00 but let’s round off), which has a complement of #0080FF. Interesting that my eye makes it lighter by 32 (decimal) points of green. Do other people have a different estimate, or concur with mine?

    1. Thinking about it some more, to get the theoretical shade of blue, you must have to take the complement of the orange (#0080FF) and then normalise it to have the same brightness as the grey (#888888). I’m not sure of the exact mathematical steps involved.

  5. A nice bright blue, yes. As an artist, I know how this works, and of course it’s an effect artists have been using for centuries. Butchers too. Why do you think they put sprigs of green parsley or kale around the meat? It’s to make the red of the meat appear much redder than it actually is. Same principle. All to do with the physiology of the eye.

  6. And despite the claim at the front it does work for some colour blond people at least. There is no one thing of colourblindness – there are different forms so a bit of a general and sweeping statement there!

  7. It didn’t work for me, and I kept thinking “What’s supposed to happen? What am I supposed to see?”

    The second time I watched it, I didn’t look at the black dot, and watched what was happening. I can understand the theory that my brain is supposed to create a contrast with the orange in order to make an illusion of the opposite (green), except… er… it didn’t. I just saw grey.

    Am I ultra-clever and logical in being immune to the psychological effect? Or was I not using my peripheral vision (i.e. was the image too small)?

  8. I saw electric blue! Its obvious the dot keeps the eyes still and the grey line moves to areas where the yellowy colour is worn out making grey seem colourful. It was interesting what the above said about peripheral vision… I’m going to try again fixing on a more central spot. I’ll let you know if that changes anything.

  9. Absolutely no relevance to eyes and colour, but does anyone remember those “SurroundSound” movies in the 70s when a low deep bass note played through the speakers made everyone shudder?

    They used it in “Earthquake” and in “Devil Within Her”, a sub-Exorcist thing, with the effect happening every time “Satan” appeared on screen, making everyone shake and scream. Except it didn’t work on me, and I sat unmoved, unaware, wondering why my girlfriend’s nails were digging deep into my forearms.

    1. I’ve always been fascinated by sublminals (did a high school termpaper on them) so I’d kind of like to experience that. I remember reading a Three Investigators book as a kid where a low tone like that was used to make a house appear haunted. Kind of cool!

  10. Seems to work for me no matter where I look, except when looking directly at it. The shades of blue did vary depending on how far out into my peripheral vision the bar was. Nice.

  11. Looks like another form of Benham’s Top illusion – can signal a full spectrum of color from a slowly timed black and white flickering.

    The interesting question which is true of Benham’s top illusion is “why do color blind people not see the illusion”

  12. i noticed that when i paused the video, the bar reverted to grey, so i suspect this is the same phenomenon where you look at a picture with inverted colors, and when it switches to b&w, you see the picture in normal color.

  13. if I remember correctly there is a physiological pehnomenon colled “lateral inhibition”: when we the eyes (retina) are hit with a specific colour, the surrounding receptors are inhibited meaning that they do not “fire” to the signal to the brain so the contrast is higher.
    I am not sure if the same applies to peripheral vision and in this case it seems like there is a different process at stake… I’m lost

  14. I saw blue straight away no green or grey whatsoever. As soon as the image came up it was orange or blue I thought I wasn’t doing it right!

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