Doesn’t need to be candy, necessarily. Money’s the first thing that comes to mind, but if that’s prohibitively costly to maintain while keeping the prizes attractive, you could play with probabilities: build a set of diverse prizes of approximately equal value, say, and instead of money or candy distribute tickets to a raffle where the winner’d be able to choose one prize. That might have some funny consequences in this experiment, though, depending on the quirks of how people think about probabilities.
Doesn’t need to be candy, necessarily. Money’s the first thing that comes to mind, but if that’s prohibitively costly to maintain while keeping the prizes attractive, you could play with probabilities: build a set of diverse prizes of approximately equal value, say, and instead of money or candy distribute tickets to a raffle where the winner’d be able to choose one prize. That might have some funny consequences in this experiment, though, depending on the quirks of how people think about probabilities.