Better be careful what you wish for and what you give this holiday season. It turns out gifts reveal a lot about both the giver and the receiver. So as you comb the store shelves for the perfect present, we’ll unwrap the psychology behind gift exchange. Marty talks with TINA LOWREY, a professor of marketing at the University of Texas at San Antonio, about the tradition, the etiquette, and what gifts say about who we are. We’ll also hear about why bundling gifts is a bad idea from STEPHEN GARCIA, an Associate Professor of Psychology at the University of Michigan. He’s the co-author of a new study, “The Presenter’s Paradox” forthcoming in the Journal of Consumer Research. And gift-giving for courtship and sex — renowned primatologist FRANS DE WAAL tells us about reciprocity in the animal world. He’s a Professor of Psychology at Emory University and the Director of the Living Links at the Yerkes National Primate Research Center.