Measuring IQ Points by the Cupful

Does it feel as if caffeine makes you more clever, upbeat and alert? Maybe that's because it does

I'm sitting in Small World Coffee, the place in Princeton, N.J., where locals go when they want to avoid the sterile trendiness of Starbucks, just around the corner. The place is packed with students and professors. Nobel prizewinners drop in frequently (John Nash, the mathematician hero of A Beautiful Mind, is a regular). But I'm not here for intellectual-celebrity watching. I'm here because my editor has ordered up a story on the question of whether caffeine makes you smarter. And without a latte—with three shots of espresso today instead of the regular two—I wouldn't feel equal to the task. Experience tells...

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