Think about the last time you heard someone give a speech, or any formal presentation. 

If PowerPoint was involved, each slide was probably loaded with at least 40 words or figures, and odds are that you don't remember more than a tiny bit of what they were supposed to show.

Much of what he found out is surprising. 

Consider, for instance, the fact that each TED talk is limited to 18 minutes. That might sound too short to convey much.

 Yet TED curator Chris Anderson imposed the time limit, he told Gallo, because it's "long enough to be serious and short enough to hold people's attention ... 

By forcing speakers who are used to going on for 45 minutes to bring it down to 18, you get them to think about what they really want to say." It's also the perfect length if you want your message to go viral, Anderson says.