Por exemplo esta:
“For years, speech instructors told their students, “tell ‘em what you’re going to say, say it, and tell’ em what you said.” While this repetitive method certainly had the benefit of hammering points home, the problem with it is that audiences know what’s coming.
As soon as you say, “What I’m going to talk about today is …” half the audience stops listening. They figure that they’re going to hear it again anyway. The other half listens hard so that they don’t have to pay much attention during the talk itself. Then, at the end, when you say, “In summary, what I’ve said today is …” three-quarters of the audience is packing up, checking their schedules, text messages, even e-mail, or literally heading out the door. You’ve lost them. Given that the last thing an audience hears from you is the most important – because it’s the part that’s most likely to be remembered – why squander those moments on something that the audience will deliberately tune out?
So don’t do it. Don’t summarize. Instead, give them a call to action.”