Boomerang Illusion

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Boomerang Illusion (also known as the Jastrow Illusion) is an effect based on an optical illusion in which two boomerang shapes appear to shrink and grow.

The optical illusion is credited to Professor Joseph Jastrow, a pioneering psychologist, who used it to illustrate optional illusions in 1891.

It's sold as part of many magic kits to children.

Publications

• Presented as an optical illusion in Simple Conjuring Tricks by Goldston (1913)
• A kind of bet in 200 More Tricks You Can Do by Howard Thurston as "Which Is Larger?" (1927)

Variations of the shape

• Noses
• Bananas
• Rainbows
• Fish

References

• http://www.tutztutz.com/2008/02/20-amazing-optical-illusions/