More than 4% of people have some form of synesthesia, a neurological condition that causes senses to link and merge. People with synesthesia may taste words, hear colors, or see calendar dates arrayed in physical space. Dr. Julia Simner, a professor of neuropsychology at the University of Sussex in the U.K., discusses the many forms of synesthesia, how synesthetes experience the world, and what scientists have learned from brain imaging studies about synesthesia. She also discusses her research on other sensory differences such as misophonia, an extreme aversion to specific sounds.