This is one from the truth-is-stranger-than-fiction category...
Michael Beißwenger was studying people chatting in the Multimedia Lab at the
Dortmund Institute for German Language and Literature, and discovered that
20% of all instant messages are never sent. You've seen this before; you see "Bob is typing..." on the chat window status line, but nothing ever arrives.
Why do so many IMs end up never getting sent? Are we so easily distracted that we lose focus in the middle of composing a sentence? New Scientist
speculates that this sort of self-editing happens in all forms of communication, including face-to-face. We think about what we're going to say, and sometimes change our mind.
After all, some things really are best left unsaid.