For better or worse, this button can influence shoppers, according to a new study conducted by the University of Miami. Facebook’s ubiquitous “like” button can entice a consumer or scare her away—depending on what she’s looking for on the internet (think facial hair remover versus great new lipstick brand). The display of a social media icon such as a Facebook “Like” button or a Twitter symbol on a shopping website increases the likelihood that consumers will buy some products, and reduces the...