Excerpt from CEOs and the Candle Problem by Graham Morehead
The only answer that really works is this: 1.Dump the tacks out of the box, 2.Tack the box to the wall, 3.Light the candle and affix it atop the box as if it were a candle-holder. Incidentally, the problem was much easier to solve if the tacks weren’t in the box at the beginning. When the tacks were in the box the participant saw it only as a tack-box, not something they could use to solve the problem. This phenomenon is called “Functional fixedness.”
Sam Glucksberg added a fascinating twist to this finding in his 1962 paper, “Influece of strength of drive on functional fixedness and perceptual recognition.” He studied the effect of financial incentives on solving the candle problem. To one group he offered no money. To the other group he offered various amounts of money for solving the problem fast.
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How could this be? The financial incentive made people slower? It gets worse — the slowness increases with the incentive. The higher the monetary reward, the worse the performance! This result has been repeated many times since the original experiment.
Will Fawcett 