Useful illusions


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The next time you are in the kitchen, try this experiment: pick up a box of butter (four sticks) in one hand and a box of saltines (four packets) in the other. Which is heavier? If you said the butter, you are not alone. Most people would identify the box of butter as the heavier object — even though, if you look at the labels, you'll see that they both weigh exactly one pound! This is an example of the size-weight illusion, and it is incredibly common. Recent research by Dr. Geoffrey Bingham and Dr. Qin "Arthur" Zhu suggests that the roots of this modern party trick can be traced back to the evolutionary origins of Homo sapiens and to the opportunities provided by a well thrown rock or spear.

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