Facebook says it conducted research for more than a year, tapping focus groups and surveys and poring over short one- to three-word comments, emoji or in virtual stickers to determine the emotions people most commonly want to express. “We have been very intentional about really understanding what people are trying to communicate on Facebook right now and how can we make that easier,” said Tom Alison, engineering director of News Feed. “We’ve wanted to make sure the product is lightweight, simple and understandable. The more reactions we add, the more complicated it gets,” he added. Facebook promised also to continue working to refine the product based on users’ feedback. The Reactions emoji could benefit Facebook, giving the data-driven company even greater insight into what interests users.