Paul Newman's character in the 1967 movie "Cool Hand Luke" earns his eponymous nickname by bluffing wildly in a poker game, winning with a hand that amounts to nothing. "Yeah, well," he mumbles, "Sometimes nuthin' can be a real cool hand."

Gambling certainly appeals to the emotions. But there must be more to it than that. Why does gambling attract so many of us, so many putatively "normal" people?

Most of us are aware that the odds are stacked against us. Yet there is something exciting about taking a risk for the chance of a reward.