There are some interesting links in this recent Economist article: http://www.economist.com/news/business/21688872-fashion-maki...

Example quote: "... interruptions, even short ones, increase the total time required to complete a task by a significant amount."

Including a book I'm going to check out, "Deep Work: Rules for Focused Success in a Distracted World"

As an anecdote, this has definitely been my experience. And it's compounded by having numerous different media: phone, text, GroupMe, Slack, email, Facebook, Hangouts, and so on. At this point, there's not a single service anybody can use to immediately reach me, because I've pretty much conditioned myself not to read anything until I feel ready to be distracted. It's a mess.