Why would someone choose a credit card with a one percent interest rate over another with a zero percent rate? The answer, says a new study, lies in the fact that consumers are often flummoxed when it comes to zero. "A reasonable assumption is that a product will be more attractive when it offers more of a good thing, such as free pictures (with a digital camera purchase), or less of a bad thing, like interest rates on a credit card," says Mauricio Palmeira of Monash University, Australia...