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This week's LabZone activity
Nov. 12, 2003
Cold Reality . . . or Hot?
One hand feels warm water and the other cool water in the same pot.
How to Fool Yourself
Get three large bowls or pots. Fill one with water that is about room temperature. Put ice water in another pot and hot water (as hot as you can comfortably stand) in the third. Hold one hand in the hot water and the other in the ice water for thirty seconds. Then plunge both hands into the water that is at room temperature. The tepid water will feel warm to the hand that's been in ice water and cool to the hand that was in hot water. So, your sensation depends on where each hand is coming from.
Why You're Fooled
This illusion was the basis for an extended discussion on the subject of reality by the famous French mathematician and philosopher René Descartes (1596–1650). He concluded from this experiment and other observations that trusting your senses was not the way to know reality. True reality can only come from ideas, including the idea of doubting one's senses. That's why he said, "I think, therefore I am." His awareness of himself defined existence and reality.
Reprinted with permission from How to Really Fool Yourself: Illusions for All Your Senses by Vicki Cobb. Text © 1999 by Vicki Cobb (www.vickicobb.com). Published by John Wiley & Sons.
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