Sunday, September 25, 2016

Some thoughts on how to structure a talk

As I will recount in a future blog post, I just went to a really fun conference at Cincinnati Children’s on systems biology. Especially cool was interacting with all the postdocs doing pretty amazing work in a variety of areas. More on that later.

As with most conferences, the talks were… mixed. Not the science, but the presentations themselves. Some were great, and some were sort of hard to follow. And some were really hard to follow. One thing I was struck by, however, is that there was far less correlation than you might think between how naturally vibrant someone is and how good their presentation was. This got me thinking: maybe part of the issue is that we always remember those presenters who are both super bubbly and super clear, and so everyone else just looks at that and says “well, they’ve just got it”, whatever “it” is, and gives up on improving. I, however, would contend that while there might be some correspondence between being "sparkly" and engagement/clarity, these are separable problems. And while being super sparkly may be a hard trait to manufacture, giving a clear and compelling talk is most certainly a skill. Indeed, I think that while it might be hard to give a spectacular talk based on skill alone, I think that almost anyone can give a great talk if they're willing to work at it and accept guidance. Being a cheerleader may or may not be part of your job as a scientist, but being able to clearly communicate your work most definitely is.

Now, there’s plenty of opinions out there on how to give a talk, and I’ve given plenty already (see also this excellent website from David Stern). However, most of these tips focus primarily on the mechanics of giving a talk, but devote little to how to structure a talk. Like, they all give some variant of the following maxims:

Basic :
  1. Don’t use text in slides.
  2. Use color appropriately.
  3. Make sure all axes are labeled and graphics are legible.
  4. Remove all jargon.
  5. Don’t go over time.
  1. Don’t use text in slides.
  2. Remove everything you thought was not jargon but actually is still jargon.
  3. Make the title of each sentence a complete sentence (or no title, but this takes more expertise).
  4. Remember that the slides are just props—you are the speaker.
  5. Identify your audience.
  6. Don’t use figures from papers.
  7. Break up multiple concepts into multiple slides.
  8. Avoid jokes unless you are actually funny. Even then, you should probably avoid jokes.
Some of these are common sense, some are obvious in hindsight. Many have some sort of principles underlying them, and I’ll leave it to you to find other websites with that information (and this great video from Susan McConnell).

Thing is, none of these rules are universal. Take, for example, “Don’t use text in slides”. I have seen multiple talks by very senior, famous PIs, and they had slides with a paragraph of writing on them that they literally just read out verbatim. And you know what? It worked! Why?

Because the structure of their talks were superb. Yet there is precious little guidance out there about how to structure your talk to make it compelling and convincing, and, by proxy, clear. Anyway, here are some thoughts on structure. (Big thanks to Leor Weinberger, who turned me on to “Resonate” by Nancy Duarte, which I found very helpful.) Keep in mind this is just my opinion, but whatever.

The main thing with structuring your talk is to realize that you are telling a story. Stories are fundamentally different than papers, the latter having to be frontloaded as much as possible. Stories, by contrast, have a narrative arc. These arcs have a formula. Do not deviate from the formula! Here’s the formula as given by Pixar:
Once upon a time there was ___. Every day, ___. One day ___. Because of that, ___. Because of that, ___. Until finally ___.
Now let me translate that to science:
Once upon a time, there was a way to measure gene expression called RT-PCR. Every day, people would grind up a bunch of cells and measure the average expression across all the cells. One day, someone looked at expression in individual cells by measuring GFP levels cell by cell. Because of that, they saw that single cells could deviate wildly from the population average. Because of that, they developed further tools, showing that this variability was pervasive. Until finally, they were able to show that this variability had profound consequences for how cells function in both healthy and diseased organisms.
Now just make that into a deck of 50-100 slides and you have a departmental seminar. :)

Let’s deconstruct this a bit. Why does this narrative formula work so well? Because it establishes tension and contrast early, and allows one to come back to it often. In scientific terms, this basically means drawing a clear line between what the current thinking in the field is (the population average is all the information we need for gene expression) and an alternative that you are going to convince them of (individual cells can vary wildly). Duarte gives the example of Steve Jobs’ introduction of the iPhone. Look at the contrast he develops! What is now: flip phones, no way to do e-mail, no music—vs. what could be: a single device to do it all.

(Random aside: it’s actually really funny watching that keynote now to see the audience react wildly for the “iPod” feature, the “phone” feature, and then clap quietly and confusedly at the “revolutionary internet communicator”. If only they knew.)

Anyway, all this to say that it’s paramount to clearly state, in simple terms, what people think now, and then tantalize them with the promise of something new, something different. To build that tension, provide hints from the literature that support your new view, like it's hiding in plain sight. Look how effective this is in Star Wars. All the little Force tricks that Obi Wan uses make you want to know more. That's like saying "Hey, everyone has been looking at gene expression for ages, and if you look around, you can see all this variability in their data that they just didn't have the tools or inclination to quantify." It is these hints of what could be sprinkled in between your description of what is that gets your audience excited about your story and helps to highlight contrast. End the first act of your story (i.e., the introduction) with some sort of major conclusion or result that provides some meat to maintain this contrast. It is that contrast that will keep them interested during the second act.

What is that second act? Before getting to that, it’s important to realize that every good story has a hero (if you have negative results, an anti-hero). And who is that hero? Your audience. They are the ones who are on a journey, the journal from what everyone thought before towards what you are going to convince them of. To borrow from Duarte, your audience is Luke Skywalker. And that makes you the mentor—you’re Yoda. Your job is to lead the hero on this journey. Think about it, aren’t the most satisfying talks the ones where you think to yourself “Man, wouldn’t it then be cool if…” and then they show exactly that experiment on the very next slide? That’s because your mentor (the speaker) is doing a good job of shepherding you, the hero, on the path.

What does the hero do in the second act? Well, there are a couple of options here. One of my favorites from many martial arts movies is the training montage. The science equivalent of this is showing a bunch of further evidence to bolster your initial, cool result. Wait, what about the alternative isoforms? Nope, that doesn't explain it. What if you use an alternative method? Effect still shows up. This is what Duarte calls "resisting the call", like Luke Skywalker (i.e., your audience) resisting the call to action to use the force and blow up the Death Star. Here, your job is to persuade.

Another approach is to "fill out the story" here. This can take the form of a digression on a side point, or further analysis. Like: "So I showed you this really cool single cell data about cancer, but it's actually also interesting for these other reasons as well, let me show you." Key thing, though, is not to give away your turning point until closer to the end, where you transition to the third act.

The beginning of the end comes from the transition from either the training montage or the fill-in-the-story sequence, which are sort of the aftermath of that first big result, to thinking about what the implications of those big results. This is the hero's turning point. Like: "So everything I showed you about single cell analysis in cancer would imply that the cells will die in this specific pattern. Does this happen?" This should lead to another major result, something to carry the ending. Your hero now has a final purpose.

Now, during the ending, it's important to come back to the beginning as well. Point out the initial state of the field again. The implication should be "See, this is how we were thinking before." In the best of situations, the contrast should be so stark that the original view should look positively quaint. This means that the hero (your audience) has transformed, and there's no going back. Then you've done your job.

This basic formula can work in long talks, short talks, any kind of talk. The only difference is how many details you leave in or leave out. The truth is that it takes time to learn this skill, and while there are some tips, there's no substitute for just carefully thinking about what you're trying to present and what works best to tell your story. I will give the following bit of advice, though. Your story has one thing more in common with a TV series rather than a movie, and that's that you can't assume people actually watched the whole thing. Even if they're sitting there, how often has something like this happened to you while sitting in the audience?
“Wow, those are some convincing results I never looked at regulatory DNA like that before and now my mind is brimming with all these possibilities hmm I wonder if SuperCuts is a pokestop that would be cool and also the FACS facility probably not oh well so what was this talk about again?”
You simply cannot assume that people listened to all or even most of your talk, and certainly not that they internalized important details. I remember someone I know giving a talk that started with some heavy quantitative framework, after which it was like "Okay, now that you've all got that, let's get into the results, all presented assuming you know this framework". That was not good. I'm directly in the field and knew some of the work beforehand, and even I had a hard time following. Things work best if you remind them of key concepts and results along the way. One nice tip (shamelessly stolen from Susan McConnell) is the idea of a talisman, some sort of visual aid that you come back to over and over to help orient your audience. For instance, if you have a framework with two competing models, show those models repeatedly, every 5-10 minutes, perhaps with variations as the story develops. Take that opportunity to reiterate the main concepts required to understand what comes next. This helps your audience reconnect with the central arc of your work.

Anyway, hope this guidance proves useful. I realize it's sort of abstract, but I've found that as my speaking skills have evolved, understanding these principles has proven even more important than all the various tips, tricks and opinions on how to construct slides. All that stuff is important, but just remember that all those rules are typically in service of the principles of clarity and engagement, and while rules are meant to be broken, you never want to compromise your principles!

Note: As I was writing this, I was definitely thinking about the standard 45-60 minute talk, which usually has at least two main results. In the case of a short talk, like 2-15 minutes, it may make more sense to shorten or eliminate the second act. Also, the transition to the third act may or may not require Any new result, but I think some version of the "what does this new knowledge imply"/"contrast with the old" is still necessary.

Another note: These are lessons that take most people many years to learn, so I wouldn't expect immediate results. But the main thing is to keep trying to improve. Many never do.


  1. I'm a big fan of thinking about narrative in a talk. One of the best pieces in thinking about this is Ira Glass's piece on Storytelling:

  2. All excellent advice. My only disagreeement: that slide with the paragraph of text read aloud by the famous professor didn't "work". It simply didn't tank the talk because the structure of the talk was good. The talk would have been better if the speaker memorized this bit or paraphrased it. People can't read and listen at the same time! (Sorry pet peeve) :)

    1. So this is an interesting point. I heard from someone else (can't remember who) that text on slides is okay *as long as you read it word for word*. That way, you listen and read together, and it works. I'm not sure that the talk would have been better if the speaker memorized this particular paragraph, dunno.