Your ads aren't working? Perhaps they're too cheerful. A study by researchers at Stanford and the Wharton School tested the theory that some audiences aren't taken with "purely happy messages and images." In their experiment, purely happy ads and those making a "mixed emotional appeal" were shown to three groups of subjects: Anglo-Americans in general, older Anglo-Americans and Asian-Americans. The first cohort responded best to the cheery ads. But older Anglos and Asian-Americans were more positive about the glad-plus-sad ads. The study says the variation reflects differing levels of comfort with "duality." More at ease with duality, the latter two cohorts didn't experience the "discomfort" younger Anglos displayed when viewing a mixture of happy and sad images.