While not scientific, the example I can think of is in How to Win Friends and Influence People by Dale Carnegie (published: 1936). In the section dealing with how people read your messages, he lists an actual letter from a company apologizing about a delay [which reads just like any corporate e-mail].

Then he rewrites it focusing on what the person reading it is concerned about: themselves. The key was to focus on the questions a reader will ask, "How will this effect me?" and "What should I do?"