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Headshot of Emily Lakdawalla

Better conference talks

Posted by Emily Lakdawalla

04-04-2013 11:37 CDT

Topics: best of, about science writing

I've been to a lot of conferences and seen a lot of talks and it's amazing to me how a bad presentation can get in the way of really exciting science. The recent Lunar and Planetary Science Conference wasn't unique in this regard but for some reason I felt pushed over the edge by it. This (very long) post is a response to my frustration about bad conference presentations. I do feel a little hesitant to set myself up as an expert on this because I know I have a lot of work to do, to improve my talks. Still, I think I have useful advice to offer.

I can summarize the whole thing in three words:

Respect Your Audience

Respect your audience. All those people in that room in front of you: they are not you. But their time is as valuable as yours. Work to deliver them a presentation that is designed for them, to inform and interest them in your work, to leave them pleased that they spent that 5 or 10 or 50 minutes of their valuable time listening to you.

Here are some questions to guide you in preparing a good talk.

  1. Whom are you speaking to?
  2. What do you want your audience to learn?
  3. What is your story?
  4. How long do you have to speak?
  5. What visuals will serve to amplify your story?

Let's take these questions one by one.

Whom are you speaking to?

Most scientists at conferences appear to be speaking to themselves, or, perhaps, to the people who will eventually be reviewing their paper. Perhaps that's all you care about, in which case you can stop reading this post right now. But if you actually want people in the room to learn anything from you, you need to think about who they are and what they will come in to the room knowing and not knowing. The wider an audience you are addressing, the more contextual information you will need to provide to them. Deleting necessary context from your talk in order to present more of what you did cuts out large swaths of audience. It is an act of disrespect to your audience. If you do not provide the people in your audience with information that they require in order to understand you, it is the same as telling them that you do not care if they understand you or not.

Let's take a specific example: let's say your work concerns using the CRISM imaging spectrometer on Mars Reconnaissance Orbiter to map clay and sulfate minerals on Mars and that you are using your maps to infer things about Mars' geologic history.

I usually think of this in terms of widening circles within your audience. You and your coauthors and/or advisors are a very tiny circle. Widen that circle a little bit to the people doing the same kind of work in your field, and you don't have to change your language very much. Widen the circle a bit more to take in other kinds of geologists, though, and you begin to run into trouble. Mineralogists who do not study Mars will understand the significance of mineral names, but they may not know what a CRISM is or what it does or what its resolution is or what its other limitations are or where clay minerals have and haven't been found on Mars. On the other hand, people who study Martian geomorphology from orbit know what CRISM is but may lack your ability to instantly mentally translate a mineral name to its chemical formula, and they might lack the background knowledge of the kind of sedimentary environments that typically produce the mineral.

And we're still talking about pretty specialized Mars scientists here. What about Mars atmospheric scientists attending your talk? What do they know? What about graduate students? What if an asteroid astronomer wanted to try to find out what's going on at Mars? What about impact crater experimentalists? What about a space journalist? A NASA administrator? A high school earth science teacher? Their students? The conference venue's A/V technician? You can widen your circle ad infinitum.

At some point, you do have to stop. You do have to identify the circle containing the people who already possess the necessary contextual knowledge that will permit them to understand everything you are telling them, and recognize the fact that some people who are there will not understand everything. Please note that I am not speaking of intelligence here. I am speaking of background knowledge. Still, context trumps data, every time. You can spend a whole conference presentation talking about TLAs to an audience of incredibly intelligent people but if they don't know what a TLA is, it's likely you won't have communicated a danged thing.

("TLA" = Three Letter Acronym.)

Really good speakers are ones who manage to communicate something to everybody in the room, no matter who they are or how much they already know. To the relatively ignorant, you should at least convey the driving questions behind your work: why should anyone care what different kinds of minerals appear in different places on the surface of another planet? What did you learn, and why does it matter? At the same time, to the well-informed, you should convey how your work has added to or broadened or contradicted what has come before it. Even the specialists spend so much time lost in the weeds in their fields that it benefits them to be reminded of the big picture.

If this is overwhelming, pick somebody in the middle of the ignorance/specialty spectrum to pitch your talk to. When I write, I am usually imagining that I am writing for a college-educated person whose degree is not in the sciences. At a conference, I'd imagine a graduate-educated person whose specialty is not the same as mine. And then I ask the next question.

What do you want your audience to learn?

It amazes me that people prepare talks without ever asking this question, but they appear to. A lot of people really spend a lot of time describing their research methods -- what they did, and what their data look like. It's easy to understand why people make that mistake: what you did is, after all, what you spent most of your time doing. But the whole point of your work was to learn something that you could then communicate to others. Don't force the audience to go through the same process you had to, in order to get to the result. You can save your audience all that work by telling them what it was you learned.

If, through your presentation, you interest an audience member in your work, they can read all about your methods and data in your paper. (That's what a paper is for.)

Here's an exercise that I highly recommend: Compose a Tweet summarizing your talk. You get 140 characters. Maybe even just 120 (there's always overhead, for a conference hashtag and your surname, or a link). You don't get to use text-speak or Esperanto. It needn't have perfect Strunk & White grammar, but it needs to be sensible, comprehensible English. In that limited space, you are not likely to say a whole lot about your methods! If you do, you are boring. "I mapped clay minerals on Mars." Who cares? "Large areas of Mars experienced rainfall over tens of thousands of years." Cool.

Make that Tweet your conclusion slide. Make sure that your talk delivers that conclusion. How are you going to do that? Well....

What is your story?

It is impossible to overemphasize the importance of narrative in a talk. You, standing up in front of an audience, are telling a story in which you are the principal character. What's your motivation? What are the big questions that drive your professional curiosity? Did you answer your questions, or was your search fruitless?

There are several fairly standard kinds of stories that work great for scientific talks. The easiest ones for space science: you are solving a mystery. Or you are an intrepid explorer who has gone to a place no one has gone before. Maybe you have fought a pitched battle with a legendary monster of a data set. (This is a great framework for a presentation about a null result; you get to be the tragic hero.)

Stories are fun. If you tell a good story, you hook your audience and then they will willingly follow you even into dark corners of your subspecialty.

Stories are also functional, especially for people in the audience who may be struggling to follow you on that journey. If, for example, you have managed to tell your audience that this is a crime story, pretty much everybody in the room should be able to understand what the crime was at the beginning of your talk. Then, if you lose them while you're talking about evidence gathering, you still have a chance of picking them back up again when you tell them: that was the evidence, and this piece of evidence led me to the perp. Even if an audience doesn't get spectroscopy or understand what a general circulation model is, they probably get how crime stories work.

Narrative is not just helpful to your audience; it's helpful to you, too. It provides a structure for your talk, and helps you determine what is crucial to conveying your message, and what is not. Which is very important when you consider the following question:

How long do you have to speak?

You cannot say all the same things in a 15-minute talk slot as in a 1-hour colloquium. You just can't. Don't even try. However, you can tell the same story, which is why I put story before talk length in this blog post. Do you have a favorite novel that's been made into both a miniseries and a movie, and maybe even a 1-hour show? Think about the differences in story among these. As you go from longer to shorter versions, you see reductions in characters; in settings; in subplots; and finally in the main plot line itself. Yet the story (usually) remains recognizable. Exactly the same process is necessary to go from a scientific paper to a colloquium to a long conference talk to a short conference talk.

It is especially important for very short talks (like at the Division for Planetary Science meeting, where the slots are only 10 minutes long, meaning 6 minutes for speech) to practice your talk and then, if it is too long, cut out information that is not needed to tell your story. You cannot solve the problem of a too-long talk by talking faster. You must simplify the story that you are trying to tell.

It is only now, once you have identified your audience, your take-home message, and your story, that you should begin to think about making a PowerPoint presentation.

What visuals will serve to amplify your story?

I've observed that a lot of people use the phrase "prepare a talk" as though it is synonymous with "compose a PowerPoint presentation." Don't do that. Please.

I don't hate PowerPoint, not at all. PowerPoint doesn't kill scientific conferences. People kill scientific conferences with bad PowerPoint presentations. PowerPoint -- or any other means of projecting visual content in front of a large audience -- is a tool, and like any tool, it can be used for good or for evil.

When PowerPoint is used for good, it serves to emphasize or amplify points that you, the speaker, are making with your voice and your body language. No matter what, your slides should serve to enhance your presentation, not to distract from it.

The number one error that almost everyone makes with PowerPoint presentations: There are too many words on your slides.

We use the same parts of our brains to process spoken language and written language. If you show me a slide containing more than a few words, I must choose between reading your slides and listening to you speak. I am physically incapable of doing both at the same time. If I try, I am liable to jump between reading some text and listening to some speech and then I miss things and I get lost. If your entire talk is written out on your slides, why the heck are you even talking to me? I read faster than I hear. You could just stand up there silently and advance your slides periodically. But of course that would be boring and I'd stop paying attention. Which is what I do anyway when you put up slides with too many words on them.

(Some speakers compound this evil of reading their entire talk aloud from their slides by using a laser pointer like the bouncing dot on karaoke lyrics, zapping each word as they read it. There are few quicker ways to make me stop paying attention either to your slides or your speech.)

Try this exercise: Put words on your title slide -- your title, name, coauthors, acknowledgments. Put words on your conclusion slide -- that Tweet I suggested earlier, and your name and contact information. On all the slides in between: no words. Just pictures. And pictures only when necessary. If a picture would not help me understand your point, put in a blank slide. Yes, I'm quite serious: a completely blank slide.

There is a great deal of power in a completely blank slide. Put one up and watch the entire audience suddenly make eye contact with you. I like to put blank slides in places where I am making transitions in talks. It is a reminder to me to remind the audience where we came from, and inform them where we are going. I can look them in the eye and check in with them to see if they are still with me.

Tips and Tricks and Do's and Don'ts

Now that I've gotten my lecture on talk organization out of the way, here's a list of bits of advice gleaned from personal experience, from the advice of friends, and from a wide variety of sources on the Internet. Unfortunately, I do not remember the ultimate source of most of this advice; a lot of it originated in multiparty hallway conversation. If you see something here and say "Hey! That was my idea!" feel free to take credit in the comments.

Speak Differently Than You Write

Do not use initialisms or acronyms in your speech at all, unless you are confident that they are understood by everyone present. A funny example of this one is "LPSC." LPSC stands for the Lunar and Planetary Science Conference. Everybody at LPSC knows what LPSC is, so that one is okay, as long as I'm at LPSC. But the people who are reading my blog? and my husband? They don't know what an LPSC is, so I will have to tell them. Every time. And honestly it's often easier to say "that conference I just went to."

Look suspiciously at any abbreviation that you are tempted to use. Ask about each one: will everyone in my audience know what I mean when I say this? If not, then I'm sorry, but you can't use it. You don't have to say "Mars Reconnaissance Orbiter" instead of "MRO" every time. You can just say "the spacecraft" or "the ship" or "the orbiter." More people will understand what you mean by that than will understand "MRO."

I hate talks where people define a new initialism in the beginning of the talk and then carry on using it throughout the rest of their talk. If you are writing a long paper that is all about something called recurring slope lineae, it is okay, even perhaps useful, to define "RSL" early and then use the initialism to refer to the features in the rest of your paper. It makes the text easier to scan. However, it is BAD BAD BAD to do this in a talk. If someone misses your definition, they will spend your entire talk wondering what the heck an "RSL" is and they will learn nothing from you.

Put two initialisms in your talk, and you become four times harder to understand. It's exponential, I swear.

The same goes for any piece of technical jargon. Jargon exists for a very good reason. Just like an initialism, jargon acts as shorthand, making communication among people who know the jargon much more efficient. But jargon is an impenetrable barrier to people who can't translate it. And if the piece of jargon that you are using is the subject of your talk, and you insist upon using it, you've just walled off a big chunk of audience. Don't disrespect your audience by using jargon they won't know. It's not good enough to define it once in the beginning of your talk.

So, wherever possible, replace jargon with a few words that can stand in for it. Yes, this takes a little more time. Which is more important to you, squeezing in a couple more sentences, or speaking to more of your audience? (There is only one right answer to that question.)

You must use less jargon in a spoken talk than in a written paper. In a paper, if I come across a term whose meaning I don't recall, I can look it up. In a talk, I can't do that. Consider, for example, the terms "stress" and "strain", which have very specific, precise meanings in physics. (Stress is a force acting upon a material, while strain describes how the material deforms, or changes shape, in response to a stress.) Even now, it takes me a split second to parse the terms "stress" and "strain", making sure I've always got their different meanings straight in my head. The professor who taught me my first structural geology course often (not always, but often) substituted words like "push" and "squish" for "stress" and "strain" when lecturing, along with appropriate hand gestures that emphasized which was the push and which was the crumpling. She used the proper terms in written assignments. The words she spoke were not as precise, but if she used only the precisely correct terms I would've understood less, not more.

Related to that, here's a cool trick: Don't use polysyllabic Latinate words when you can use Anglo-Saxon ones. Speak these two sentences: "Curiosity remained immobile." And: "The rover stood still." Both convey the same information; they work pretty similarly, when you're reading silently. But you can be so much more emphatic speaking the second one. Here's another comparison: "The compressive stress resulted in a crustal length reduction of thirty-one percent." And: "The crust got squished to just two-thirds as wide." Use the first one in your paper. Speak -- and gesticulate -- the second one. I wish I could remember who told me this trick, because I love it.

Whatever you do, don't call this "dumbing down" your language. You are not dumbing it down; you are oomphing it up. (Yes, I did just use "oomph" as a verb. Sue me.) Language is a tool for the communication of information. Use the words that will produce the strongest signal in your audience's receiving brains.

Simplify your sentence structure. In a technical paper, a single sentence can span a whole paragraph. Modifying clause piles on top of modifying clause. It's a way to armor sentences against criticism. But excessive dependent clauses are deadly in speech. If I lose track of which noun your lengthy list of clauses is modifying, I lose the whole sentence.

Simplify. Finish making one statement before you move on to another. Don't conjoin sentences when you can split them into separate ones. If your audience contains people who speak English as a second language, simplifying your sentences will greatly increase how much you are communicating to them.

If a point is important, repeat it. You can't bold it or underline it when you're talking. But you can repeat it. Repetition is verbal underlining. It also functions like putting up a blank slide. Repeat something and you'll start making eye contact with your audience again. Say something three times and they'll all be looking at you.

Passive voice stinks. Actually, this is as true in written text as it is in speech. Don't say "it was observed," say "I observed." A lot of dramatic things happen in space, but we suck all the drama out of them by making sentences passive. Rearrange your sentences into subject-verb-object form and see how strong a verb you can stick in there.

Don't go over your time. DON'T GO OVER YOUR TIME. Speaking so long that there is no time for questions informs your audience that you do not care what they think of your work or whether they understood your presentation. Speaking so long that you run in to the next speaker's time informs your audience that you think you are more important than the next speaker and more important than anything else the audience had been planning to do at that time. Both are insulting and disrespectful. You look like a jerk if you go over your time.

If, when you talk, you seem to vary widely in your talk length, bring your smartphone to the podium and run an app that has a countdown clock, and make sure the screen will stay on through the length of your talk. If you seem to be running long, do not talk faster. That will reduce, not increase, what audiences take away from your talk. Skip ahead and finish on time.

Anyway, if your talk length varies widely, odds are good that you're going down side paths that you should not.

Your slides have too many words, and other problems

If you must put words on your slides, use very few. No complete sentences. A title for a slide is okay. If you are talking about something that may be unfamiliar to some (say, recurring slope lineae), please show a photo of that thing and label it as being that thing. That will aid understanding. But don't put a several-sentence definition of the thing on your slide. Then people will read your definition instead of listening to you.

No text below 20 points. If most of the audience can't read it, why bother putting it on the slide?

Graphs can be a really big problem. There is a tremendous amount of information in a graph. Different color symbols! Different axes! Which way do the axes increase? Are they logarithmic or linear? If they are linear, is zero on the graph or are you just showing me a little bit of the range? Are there error bars or not? Are the lines thick enough to see? Do the colors show up on the screen? Can I even read the axis labels? Even if the font is big enough, are the labels so low on the slide that the rows of heads in front of me are blocking them? Which part of all of this is actually important to the point you are trying to make? And how should I figure all of this out while you're talking at me? Think very carefully before you include a graph in your talk, and then be prepared to spend minutes explaining it. And take out every line or label that is not strictly necessary. Graphs that are suitable for papers are generally NOT suitable for talks.

There are some kinds of graphs that have a very common form so are instantly recognizable -- to people who possess the necessary background knowledge. Those of you who live and die by R-plots or infrared spectra probably have to show them in your talks. Sometimes. Maybe not as often as you do now, but sometimes. But make sure that, one way or another, you present them in a way that someone who doesn't know what the heck an R-plot is will still understand the point that you are trying to make by showing it. Unless your talk is to the R-plot Appreciation Society.

Equations are even worse than graphs. Seriously, don't put equations on your slides. On very rare occasions I have seen people show an equation and effectively use it as a means to convey to the audience how much more strongly one term controls the behavior than another term. You wizards who can do that effectively may go on putting equations on your slides. The rest of you: don't.

Data tables: BAD. No. Don't.

Approximately one in ten of the men in your audience is color-blind. What this means: never, ever use a ROYGBV spectrum to represent a continuously varying property. Vischeck is a super website to use to ascertain whether your graphics will be incomprehensible to the color-blind.

One thing per slide. You can only say one thing at a time. What is on the screen should be serving to emphasize what you are saying right now. If it is illustrating something else, it confuses rather than aids people in understanding what you are saying. It works very well to start with a relatively empty slide to which things get added as you speak -- for instance, starting with a photo and then adding circles around interesting features as you point them out. That's a great method when it works, but if you find yourself in a situation where you are not controlling the clicker and you have to verbally cue the poor A/V person to advance to the next time-step to put every circle and line on your slide, then you're in trouble. Still, I have found that A/V techs (or the session chair or whoever is driving the presentation) are getting better at listening and queueing slides that get built incrementally in this way; speakers just point or wave and the tech clicks.

Without words, your slides will almost certainly not be able to serve as a stand-alone record of your presentation. If your slides could stand alone, then your presence wouldn't be necessary. Obviously this means that you can't make a presentation by reading from your slides. People who read their slides to the audience are usually facing away from the audience. It is disrespectful to your audience to turn away from them, and moreover, it looks stupid. You're going to have to have separate notes. I mostly don't use notes when I speak except when I'm very nervous, but I still have notes from when I was planning my talk, and I keep digital copies of those notes in a folder with my PowerPoint presentations. If your PowerPoint presentation is going to be archived somewhere, feel free to add a slide after your final one and just paste in your notes there.

DO put your name on your slides, maybe even your abstract number. I can't tell you how much of my time in the audience at conferences I spend shuffling around the program trying to figure out the name of the person currently giving the talk so that I can find and read the abstract later. (This is usually because I was struggling to compose a tweet-length summary of the preceding talk, and I missed the introduction of the next speaker; or because the previous speaker in a different room ran long, and I showed up late to the current talk.) Put your name and maybe your abstract number in the corner and you make my life so much easier. You also make it more likely that you'll be contacted after your talk is over by someone who was interested by it. If you want people to be interested in your work beyond the few minutes of your talk, especially if you are a relatively obscure person in your field (say, a student), put your name on every slide. If nothing else, make sure to put your name and contact information on your conclusion slide.

Your last slide is the one place where you ought to have a sentence. I like one Tweetable sentence that summarizes your talk. Don't make your final slide say only "Thank You" (though there's no harm in also putting that on the slide) and especially don't make it say only "QUESTIONS?"

Odds and Ends

A word on the number of your slides. It's a commonly cited rule of thumb that you should have about one slide per minute. I think, though, that that assumes that people (or you) will be reading your slides. If you have a slide full of 20-point font, it will probably take about a minute to read that slide aloud. This one-per-minute rule of thumb doesn't work as well if your slides aren't word-heavy. And it makes the PowerPoint presentation drive your talk organization, rather than the other way around. So I don't find that rule of thumb particularly useful. Focus, first, on what you want to say. Have slides at appropriate places to emphasize what you are saying. If you can't say what you need to say in your allotted time, you need to say less. Eliminate slides or slide content that are no longer needed to support what you are no longer saying.

A word on animations. I have to say that this recent LPSC is the first conference I've attended in a while where I did not witness many train wrecks involving animations not playing properly. Still, if your presentation contains an animation (and they can be awesome visuals), make sure you have tested that your animation works. If you do not have an opportunity to test using the exact system that is employed in the conference hall, have a backup plan that does not involve berating the hapless A/V technician. I like animated GIFs in PowerPoint presentations because they always seem to work. If you know you will have control of the clicker, an even easier way to do a not-very-many-frame animation is just to put one frame per slide and advance them manually. That will work even if (horrors!) your PowerPoint is turned into a PDF.

A word on anxiety about forgetting your talk. I think a lot of people write their entire talk on their slides because they're afraid they'll stand up in front of all of those people and forget what they want to say. I have a lousy memory, and find it impossible to memorize the specific words I want to use; getting away from using text on slides as a crutch was a serious challenge for me. PRACTICE helps a great deal.

Here's a method I use, especially for short talks. I try to memorize the first sentence I intend to say about each slide or sequence of slides. Then I speak more off the cuff for a few sentences about that part of the story. While I am doing that, I visually check in with my audience to make sure they are with me. When I advance the slide, I glance at it, and that triggers the sentence I intended to say when I advanced that slide. If I have words on slides, they are usually just titles; those titles also serve as my cues to help me get my intended first sentence out.

A word on what to wear. When you are speaking at a large meeting, you should be slightly better-dressed than your audience; being better-dressed commands attention and that's what you're there to do, to command attention. At geology meetings, any amount of effort spent on your appearance will make you look sharper than your audience, so this is not a hard standard to meet. Particularly if you are young and have not yet earned much in the way of professional respect, dressing nicely is a way of adding to your respect-worthiness. Personally, I view a certain amount of effort spent on personal appearance as a sign of respect to the people who have to look at you. It's a sign that you take yourself seriously, which is a suggestion to me that I should also take you seriously.

There are people who successfully pull off not being dressy. These are usually senior and/or highly confident people, who can succeed without the respect boost that dressing nicely gives them.

For women: the fact that you get to use makeup when you give a talk is a rare situation in which being female is an advantage; use it! Even if you (like me) never wear makeup on a day-to-day basis. When you are on stage and are fighting for people's attention, it is easier to make eye contact with people if your eyes are more noticeable. It's easier for people to read your lips if they are easier to see. If, like me, your skin tends to get even more red than usual when you feel attention on you, wear foundation and powder to minimize how flushed (and hence nervous or embarrassed) you look. You don't need to look like Tammy Faye. Even just a subtle quantity of eyeliner and mascara and lipstick will make it easier for you to connect with your audience. That being said, you are on stage and it's actually hard to wear too much makeup on stage. Though if you don't want to look like a freak in the hallways, you shouldn't go overboard.

(Men: I challenge some of you to use a little makeup before a public talk. Even just a bit of powder to knock down shiny skin and prevent your specular reflections from drawing attention away from your eyes and mouth. The pros do it.)

For either women or men: if you have long hair, make sure it does not fall forward where it might brush a lavalier microphone.


I welcome both!

Further reading:

Scientists are Humans, Too

Giving an Academic Talk

Spectacular Scientific Talks

End of the Rainbow  

Advice on Giving a Scientific Talk

See other posts from April 2013


Or read more blog entries about: best of, about science writing


Mark Gooch: 04/04/2013 12:07 CDT

Very well said. A copy of this material should be given to anyone who is preparing a lecture.

Patrick Donohue: 04/04/2013 12:14 CDT

Related to "keep your audience in mind", in themed sessions people will sometimes refer to earlier talks and say "so and so already gave a good overview of this method or process, so I'll basically skip over most of the details". They are a) assuming everyone was there for the entire session and/or b) were paying enough attention to remember method or process X clearly. I spent an entire talk confused about how a presenter was performing crater counts because he never described the N(20) and N(64) method (which is counting only the number of craters with diameters larger than 20 or 64 km, respectively). It's a ubiquitous method in crater counting studies, but I'd momentarily forgotten and was distracted the whole talk. And if you can breeze over a process/method explainer slide, then it probably should have been shorter in the first place.

Donald Morrow: 04/04/2013 12:20 CDT

Dr. Lakdawalla, thank you so much for preparing this well-written and easy to read guide (dare I say, "rules") for giving presentations. I certainly learned a few things.

Stephen Uitti: 04/04/2013 02:27 CDT

Don't let Emily fool you. She's an expert at presentations. I start my presentations by asking the audience to interupt me with questions when they have them. I take questions mid-sentence. I try to let other audience members answer questions. One of my best presentations included a lively audience discussion where I didn't even have to moderate. This isn't easy to do. I'm still working on it. You have to go beyond respect and empower the audience, somehow. On my TV show, there's no interaction. Some of my segments are as short as 90 seconds. That's like Twitter. I don't read from a script. We use a white board with an outline, and maybe some facts. We go for relaxed conversation with feeling. Text on images are all labels, like "Venus". An attempt is made to explain that it's the planet Saturn near the bright star Spica in the constellation Leo. People read to themselves about three times faster than you can read out loud. But if they're doing that while you're reading, there's cognitive disonance. They'll either miss both, or be bored while you catch up. Images for our show are 704x480 (NTSC format). Expect that the edges will drift off the screen. The colors on the TV are often not very close to the colors on my computer. I have a script which scales, fills to retain aspect ratio, and adds borders. Planetarium image labels must all be removed and replaced with large, bold san-serif text in a contrasting color. I've probably been doing it right, but now I have a tool to check for color blindness - thanks Emily. When pressed for time, I used to sacrifice humor to jam more content in. Professor Binns (only in the Harry Potter books) would have been proud. Totally a bad idea. For the upcoming May show, I introduced the Eta Aquarids with "Astronomers come clean with a meteor shower". I told them when to look. I hope I told them to dress warm. In a live presentation, you can gauge your audience by the response to a one-liner. My current favorite: "I know it's time consuming, but I like to eat seconds."

Laszlo Molnar: 04/04/2013 03:19 CDT

An astrophysicist, Don Kurtz, has written a similar guide a few years ago. I especially like the intro where he quotes Lewis Caroll: "Early in Alice’s Adventures, after she has fallen down the rabbit hole following the white rabbit (who is late for a birthday party), Alice eats a small cake that makes her grow to a height of 2 miles! This is a crime in Wonderland (rule 42, in fact) and she is tried by the King of Hearts. The white rabbit is required to give evidence at her trial, and asks, “Where shall I begin, please Your Majesty?”. “Begin at the beginning,” the King said, very gravely, “and then go on till you come to the end: then stop.” This was wise advice 150 years ago in Wonderland, and it is good advice now for giving a scientific talk: “Begin at the beginning, and then go on till you come to the end: then stop.” It is the last of these instructions that is the hardest to obey, “then stop,” and we will return to that. But for now let’s begin at the beginning. " You can access the entire paper here, it is worth reading: (the pdf and scanned gif versions are open access)

David Draper: 04/04/2013 04:14 CDT

Brilliant, brilliant, brilliant. A couple additions: I also use your suggested technique of memorizing the first thing I am to say in a talk; but I also do the same for the LAST thing. Typically this is on my summary slide, containing the few bulleted points to take away, which I briefly and simply paraphrase. I memorize that last paraphrase sentence, deliver it crisply, and then simply say "Thank you." Everyone knows the talk is then over. It's terrible when speakers just trail off, with something like "...and, uh, I guess, uh... yeah, that's about it." Zzzzzzzz. On laser pointer use, I learned a trick from Darby Dyar back in the days before laser pointers, when they were light-saber sized flashlights using incandescent bulbs to project an arrow. She would always cradle the light in the crook of one arm and simply turn her body slightly to direct the arrow. The same is even easier to do with a laser pointer: just rest your pointer hand on your other arm and twist ever so slightly to direct the beam. It doesn't bounce around, and it is impossible to do that incredibly annoying swirly thing, drawing circles constantly until your audience is hypnotized. Plus, press the button only for a moment to draw your viewers' eyes to whatever it is you want them to look at, no need to leave it on any longer than that. Then repeat when you want to direct their attention elsewhere.

Emily Lakdawalla: 04/04/2013 05:20 CDT

Thanks, everyone. Laszlo: That's a great article and I've added it to the "Further Reading" list. David: Darby is one of my favorite people. For everyone: Here's a useful comment from Sarah Horst via Facebook: "Something I told one of our grad students that she says has really helped her for long talks...have a plan for what you are going to do if you run short or you run long. Know which slides you are going to skip and HOW you are going to skip them. Having a countdown helps you keep track of time but if you get behind skipping a bunch of slides without doing it in a sane way causes just as many problems as talking really really fast."

Carolyn Brinkworth: 04/04/2013 05:37 CDT

Emily, I'm going to completely take you to task on your advice about wearing makeup - it's a crazily gender normative thing to say to a group of people. Far more important is feeling comfortable and confident on stage in front of everyone. You're absolutely correct in your assertion that you should be better dressed than your audience but, personally, I feel like a total idiot wearing makeup and wearing a skirt, and honestly, I look like I'm in drag. Far better for me to wear a nice suit, eschew the makeup that makes me feel uncomfortable, and go up there feeling like myself. The less attention I'm paying to myself, feeling self-conscious, the more attention I pay to my audience and the message I'm trying to communicate. That, in my opinion, is showing them the greatest respect. Confidence is 80% of giving a successful talk, and feeling self-conscious is the biggest confidence killer in the world. Dress well, but dress as yourself.

Ralph Lorenz: 04/04/2013 06:05 CDT

Excellent article ! As you say, the overriding consideration is think about the audience. One tip, if you are not speaking on the first day, is pay attention to the room layout - is it big or small? Is the bottom part of the screen going to be obscured to much of the audience? These should condition whether you can afford to use the whole slide and how small details can afford to be. Also, pet peeve. I never, ever want to hear the words 'you can't see these (lines/numbers/points/whatever)'. If they're not going to be visible, don't ****ing show the graph! Make the graph better so people CAN see them..... I love your remarks about narrative. There isnt always time for it, of course (e.g. DPS) but sometimes it's fun to throw something unexpected in the beginning of a talk and then arc round at the end to show why it was relevant (I did that with Whales in a dust devil talk once..)

Emily Lakdawalla: 04/04/2013 06:32 CDT

Carolyn, I hope you noticed that I advised men to try using makeup too. Bill Nye keeps powder in his briefcase and uses it whenever he stands in front of an audience -- as does most any other male actor I know. Every stage actor, ever, uses makeup for the purpose of adding emphasis. There's nothing wrong with not using it, of course. I think of it in D&D terms. A nice outfit gives me +5 respectability. Eyeliner gives me +5 in the likelihood that when I try to grab somebody in the audience by attempting to make eye contact with them, I will succeed. It's not about doing a gender-normative thing. Putting on eyeliner is like increasing the font size of your eyes. Men ought to try it too -- the only reason I didn't say that in the article is because I didn't figure it was advice that anyone would follow. If you are ever on television, a makeup artist will do this for you. Ralph, I consistently use you as an example of a good speaker/writer so I am very pleased that you like this article!

Cynthia Phillips: 04/04/2013 10:10 CDT

Great tips, Emily - I'm going to send this on to my students (some of whom are giving talks next week at a conference!). I'd like to disagree with one of your suggestions, though - as someone who takes in information much better by reading it than by listening to it, I really like having text on slides. By putting up just an image, you're leaving out some learning styles - having an image, a phrase of text, and the words of the speaker means that you maximize the chances of your audience finding at least one delivery mechanism that works for them. And thanks for the equal-opportunity makeup suggestion, though I'll be another to say that it's non-mandatory - I usually tell my students to dress to be listened to, not looked at.

TheSpacewriter: 04/04/2013 10:10 CDT

Excellent points all the way! I, too, was a bit concerned about the makeup advice, but since I spend time on camera and on stage doing astronomy presentations pretty frequently, I think that your point is well made about speakers of either gender using makeup appropriately. As much as we all might say we don't judge by appearance... we actually do, and in media, professional appearance includes makeup. I will also reinforce the idea that making your ideas understandable to people is NOT dumbing down. It's called "communication" and it's what we do when we share our science with audiences -- from the most technical groups to members of the public. Thanks for taking the time to write down what most of us who do public presentations have known innately for some time. Very good points! CCPetersen

Carolyn Brinkworth: 04/04/2013 10:45 CDT

Emily, of course I noticed that you advised men to wear makeup too, but I also noticed that you instructed women to use the works - eyeliner, mascara, lipstick, whether they normally wear it every day, while throwing out a small challenge to men to try a bit of powder. If you'd simply said "I recommend that everyone wear makeup" then that would be treating the two genders the same. Look, I realise this isn't a huge issue, and I'm probably seeming really pedantic here, but this kind of double-standard really grates on me. Especially considering all the articles on benevolent sexism that have been flying round the web this week. I guess this just felt like yet another post advocating double-standards for male and female scientists. I guess my point is that eyeliner gives *you* +5 points in grabbing attention, but there are plenty of people who would suffer from a -5, because they are so self-conscious about wearing it that it detracts from their confidence on stage. I keep coming back to the best advice being that you should feel comfortable on stage, so that you're not thinking about yourself, just about your message and your audience.

Michael Richmond: 04/05/2013 08:00 CDT

This is a very well written guide for anyone who is going to give a scientific talk. I've just sent an E-mail to our astronomy graduate students here at RIT which suggests that they read your column and consider the advice carefully. I've been teaching and giving public talks for long enough that I feel comfortable not dressing up (and, given my speaking style, it's probably better that I don't wear good clothes), but I can't deny that appearances do make a difference. I've been interviewed on camera several times, and by golly, I wish I had been wearing a bit of makeup. Keep up the excellent work, Emily!

Alfred Bortz: 04/05/2013 12:40 CDT

Excellent. Perfect for your audience! :) I often address the topic of how to write for young readers--or any audience you might choose, and I use a TLA. (Aside: TLA is a TLA, of course.) Mine is APT, for audience, purpose, tone. Of source, it is in the fleshing out of each letter that I get my message across, aptly, I hope.

David Draper: 04/05/2013 02:20 CDT

All of that, and spot-on D&D references to boot. It really does come down to your primary mantra: Respect your audience. Do that, and you'll roll a critical hit nearly every time!

Frank Kraljic: 04/05/2013 08:50 CDT

Does D&D stand for Dungeons and Dragons? (hahaha) When directing my TV series on STEM careers (Science Technology Engineering and Math), over half of the researchers, experts and professionals we feature have difficulty simplifying material to the length of a couple tweets. On TV especially, long explanations result in the audience changing the channel. Having some planetary research background, I believe the reason for this over-explanation stems from the general motivation of scientists: to answer, why or how? Accumulating knowledge results in more questions and a dissatisfaction with the present answer without deeply qualifying that answer. How would one describe the events leading to a supernova? Does one explain every nuclear burning phase leading the collapse of the iron core, or would a general description of the process leading to the collapse suffice? For TV's general audience, it's the latter, unless the show is Into the Wormhole, but even then details of the process are succinct. This where I appreciate your point of asking, "What do you want the audience to learn?" and specifically, the tweet analogy answer. That "tweet" answer should encompass not only the purpose of a talk, but virtually every point building off the previous. Looking at speakers/presenters like Steve Squyres, Bill Nye, and Tyson Neil Degrasse, this method is one of the ways they captivate audiences through detailed and sometimes complex content. And for TV, a necessity. I look forward to using points in your article to assist our featured guests. Thank you.

Leigh Dudash: 04/06/2013 06:09 CDT

Emily, that was so well said, and so important, that I actually logged on to tell you so (this is the first time I've done that). I only wish that I could get back the many hours of my life which were wasted as I stared glassy-eyed at a slide full of equations in 10-point font. It seems that too many speakers are focused on intimidation, rather than illumination, of their audience. I especially like your blank-slide advice. I will start doing that instead of just leaving the previous slide in place, which I realize now is probably a distraction.

Moses : 04/08/2013 12:50 CDT

I just used this post to rewrite a talk that I've given at least a half-dozen times to k-12 students, college students, and astronomy clubs. I've given it in a variety of lengths, from fifteen minutes to over an hour. It's always been very well-received. It and most of my talks already conform pretty well to these suggestions. Overall, I'm in agreement with most of this advice, especially about time limits. I've never worn makeup to give any talks. It may help, but I couldn't apply it myself so I would just look like something out of a horror movie. ;) I have one minor quibble with the suggestions: I agree with Cynthia. Written words are not inherently bad. What's definitely bad are full-length sentences. What's evil is reading those sentences to your audience. Perhaps almost as bad, I believe, are graphics without any sort of anchor. IMO, unless the speaker is brilliantly attention-capturing—very few are—then an image all by its lonesome can be just as bad as too much text. Especially for those unfamiliar with the graphic. For example, showing pictures of craters without their names (or sizes) and then talking about the craters using those names will lose people, even if one has already introduced the craters. I use slide titles as anchors for my audience as much as for myself; the text is there, it might as well mean something to everyone, not just me. So, I rarely use single-word titles. I also label graphics with text, numbers, and other marks, depending on the needs. You give an example of skipping from session to session. Walking in on a talk in progress, with just a photo of some feature you're not familiar with is probably going to cause you as much trouble getting up to speed as any other poorly-designed slide. Even if you've been listening to the talk from the beginning, there are some graphics that really would be better replaced or at least augmented by text. For example, comparing the sizes of several features or the time scale of several events can sometimes more effectively be done with text rather than a graphic. Sometimes, it can and should be done with a graphic. Obviously a slide-sized table is just as evil as reading your text to the audience. I think that the point is that there's got to be a compromise between too much and too little. This goes for much of the advice: too many blank slides is going to be distracting: use wisely. Too much text can be mind-numbing: use wisely. Too many graphics on one slide can be distracting: use wisely. etc. But every-so-often it's effective to use these things. The key is knowing whether you, the speaker can be effective in using a given tool to transfer knowledge. If you're not paying attention to your audience, to your slides, and to your speaking style, then you'll never know...

squawky: 04/08/2013 02:41 CDT

Love this post - hope you don't mind if I share it (properly attributed, of course) with classes... especially the research methods class where giving talks is one of the syllabus topics. I find often that the best laid out talks come from grad students - in terms of giving background and defining acronyms, at least. It always feels a bit repetitive when the fifth speaker in a row explains the common acronyms. but you share a good point about the people in the room who may not have been there for the previous four talks. It brought to mind a session at last year's LPSC that discussed some of the Diviner results - I got almost a bit irritating at hearing similar explanations of the Christiansen feature (CF) from each speaker - but found that I didn't remember that information when I saw similar talks this year - and was lost when that information was not in the presentation. One trick I've tried to use (both in classes and meeting talks) is to put information on the slide that I don't plan to talk about but still want to include - lat/lon coordinates or image numbers, for example, or citations (someone once told me that you should either put citations on your slides OR say them out loud - but never both). If someone in the audience is really curious about where the image is from or where that bit of information came from, they can write it down off the slide... The hardest part for me with keeping to the time limit is when my practice talks run too long and need to be cut - once the a adrenaline kicks in on the podium (which it does), I tend to drift back to those earlier talks and start to add back in the material I've taken out. Presenter notes (the ones in PowerPoint/Keynote) may help with that, if you are able to see them while you are speaking. I really do like the presenter display in the iOS version of Keynote - it shows the clock time along with either presenter notes or the next slide (wish it could do all three). Now I just need to convince my iPad that animated GIFs should run in Keynote, too...

Emily Lakdawalla: 04/08/2013 04:32 CDT

Moses -- thanks so much for your test and response of this. When I first drafted the article, the "no words" advice was written as just a try-it-out exercise, but the more editing I did, the more carried away I think I got on that point. I do find few to no words to be very effective for public talks (talks to kids or at geek party-like events), but heavier use of words as signposts in professional talks is probably a more appropriate approach. The idea is still to amplify or underline what you're saying. I'll definitely be revising this post based on feedback here and elsewhere! Serenia Diniega also made good points about the value of *some* words on slides on Facebook:

Moses: 04/08/2013 08:29 CDT

I like to use text on *some* slides (other than slide titles, of course) in my public talks (schools and astronomy clubs) when (I think) it helps the audience better grasp what I'm talking about, for example, comparing timescales of events that take between seconds to millions of years: sometimes itemization of three or more comparisons is easier and clearer with text than with graphics, but if it's done poorly it turns into a mess. This preference comes from trying several different methods and settling on this being the one that generates fewer looks of confusion and fewer requests to go over it again... That said, I would be super happy if someone could point out a better way to present those kinds of comparisons, of course.

Michael Nolan: 04/08/2013 10:00 CDT

Once upon a time, the late 1990s, I think, at conferences it became ubiquitous to have two overhead projectors. Once we realized it, this was a great way to work: words on one, preferably the conclusion slide that you left up the whole time, and pictures on the other. PowerPoint killed all that, and it hasn't come back, probably because PowerPoint is designed for sales presentations, so there's no interest. Of course, there were always the people who used it to give the audience two full pages of equations, but it did make it a lot easier to do an adequate talk.

Jim Secosky: 04/09/2013 10:01 CDT

Thank you so much for your excellent instructions. I hope to give some talks this summer and will use your ideas. One point I would like to make about using text on slides is that some people's speech is difficult to understand. In some cases, the only part I understand is what is written on the slide. It is also great that you comments motivated so many other speakers to add their advice.

Artemis Westenberg: 04/10/2013 05:48 CDT

I could not agree more with your blog and I will try to have many of your suggestions implemented in our upcoming Humans to Mars (H2M) summit. I hope my speakers will be open to suggestions.

Martin Haber: 04/10/2013 03:37 CDT

I would recommend to state conclusions on your slides instead of talking points. A conclusion forces the speaker to make up their minds and do science. A talking point is too easy. Also, if someone is not listening (or just gets the slides) they can just read the point.

Martin Haber: 04/10/2013 03:53 CDT

Regarding number of slides, I think 60-80 slides is way over the top unless you are talking for hours. 30 for an hour is plenty of information for any audience except maybe astrophysicists or rocket scientists (I'm just an old country chemist).

Stephen Uitti: 06/13/2013 11:27 CDT

In teaching, the lecture gets 20% audience retention. Hands-on activities get 55%. Getting the audience to teach gets 95%. We use the lecture for practical reasons. One thing that came up recently is that in clinical trials, hand gestures improve audience retention.

Emily Lakdawalla: 06/21/2013 06:21 CDT

Sarah Horst just shared this talk on Facebook; it's super.

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