Hype about a product such as the iPhone is also self-perpetuating: Hearing that people are waiting in line for hours to get a product can make others want it more, said James Mol, psychologist at Providence Portland Medical Center in Portland, Oregon.

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"We know that through the Prohibition, for example, when you ban any product like alcohol, that people tend to be more interested in the product, " said Dr. Gigi El-Bayoumi of George Washington University Medical Center.

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