The Zen of Presentations, Part 31: Redundant and repetitive

In our previous installment, commenter Sproglet mentioned some very common advice:

• Tell them what you’re going to tell them.
• Tell them.
• Tell them what you just told them.

I’ve never been crazy about that advice, particularly for a typical academic conference talk. Most conference presentations are 15 minutes. Given that the usual problem is managing to cram the complexity of research into a 12 minute presentation (so you have time for questions), every second is valuable.

Writer Michael Crighton once described how one of Jurassic Park’s scientific advisors (Jack Horner, maybe?) bemoaned that the paleontology scene in the opening of the movie wasn’t as realistic as it could be. The advisor had even suggested to Steven Spielberg a scene that was a little more accurate. Crighton asked how much longer the scene would be than what was in the movie. “About a minute.” Crighton replied it was no wonder it wasn’t used, because a minute is a long time in a movie.

If you’re the sort of person who watches the bonus features on DVDs, you’ll recognize this as one of the main reasons that scenes are cut. You will often hear a director saying, “This was a really nice character beat, but it didn’t provide us with any new information,” or, “We just wanted to get the plot going as fast as possible.”

That economy of storytelling is something many presenters would do well to imitate.

Few movies lay out what’s going to happen in the first act of the film. (Exceptions: Caper movies, where the whole idea is to lay out a plan in detail, then watch where it goes wrong.) Likewise, movies usually don’t end with a series of flashbacks or dialogue recapping the plot the characters have just gone through.

Yet I frequently see people using “Outline” slides (some of my colleagues require their students to have them), with a series of bullet points that are often almost identical to the list of standard sections in a scientific paper. I do not find this valuable in a short talk, particularly given that many technical talks do not have enough introductory material.

I do think repetition is good, particularly in a teaching context, where you want people to retain information for long periods. But there are more natural ways to do it than having a bland outline at the start or an instant replay at the end.