# A Big Question For You and Excel Optical Illusion #33

For the past nine months it has been my pleasure to bring you this blog.
This is my 84th blog entry!

During this short period I have been sharing a very wide range of topics and sample workbooks that I thought would be interesting and instructive. But it occurred to me this week that I should really be asking you what you would like to see going forward. So here is a small survey that will help guide the future direction of this blog.

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On another note, Excel Hero Academy is coming along great. I plan to make a major announcement in the next couple of days!

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This week's Excel Optical Illusion is called The Koffka Ring. Like last week's I found this at the MIT collection.
From the MIT site:

Koffka was a Gestalt psychologist who studied the importance of grouping in perceptual phenomena.

In the case of lightness, he showed that a gray ring on a light/dark background looks uniform, but when the two halves are split, they look quite different. A new variant is also shown, where the halves are slid vertically, giving an impression of transparency.

Even though the half-rings are set against the same backgrounds in each case, their appearance depends on the overall spatial configuration.

My Excel version is an interesting XY Scatter chart. In this case, I am not using any graphics copied to markers, just normal series lines. The animation is done in a hybrid fashion between the method used in the animated business charts and in last week's animated shapes illusion.

Here is the illusion file:

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Why do I share these optical illusions? The techniques that are used to make them, when mastered, can be used in many other Excel projects, in charting, formula crafting, and formatting. Learn them. They will aid you on your journey to become an Excel Hero.

Here is a list of other Excel Optical Illusions here at Excel Hero:

The Haze Illusion
And here's a list of other animated charts on Excel Hero:

- Excel, A Presentation Platform (Number Spiral)
- Lilac Chaser (Optical Illusion)
- Stereokinetic (Optical Illusion)
- Illusory Contours (Optical Illusion)
- Breathing Square (Optical Illusion)
- Enigma (Optical Illusion)
- Two Sinusoids (Optical Illusion)
- Perpetual Collisions (Optical Illusion)
- Freezing Rotation (Optical Illusion)
- Reverse Spoke Illusion (Optical Illusion)
- Stepping Feet Radial Illusion (Optical Illusion)
- Swimming Fish (Optical Illusion)
- Mutually Interfering Shapes (Optical Illusion)
- Kaleidoscope Motion (Optical Illusion)
- The Haze Illusion (Optical Illusion)
- The Koffka Ring (Optical Illusion)

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