Giving science talks

Some advice on slide design and presentation so your audience doesn’t cringe or fall asleep. Designed for undergraduates, but hopefully useful for other demographics. Timing suggestions below are based on a 20-minute talk.

Presentation content

Title slide: Title, your name, institution, and e-mail address if you think people would be interested in contacting you. This slide will be displayed as you are getting introduced. Don’t read the text to your audience, unless you know that it contains people who clearly cannot read. Make sure you have an interesting photograph on this slide, too. [2 min, 1 slide]

Introduction: Show some pretty visuals (photographs, SEMs, drawings, paintings, Quicktime movies, sound files) of your subject and get your audience excited about the “issue” or question; put your issue in the context of several already-published articles from the primary literature; summarize (very briefly) your past research, if any, on the topic; provide clear statement of hypothesis, and give “road map” of what you will talk about in the rest of the talk. Avoid slides with a lot of text. [2 min, 4 slides]

Materials and methods: Show more pretty visuals of your organism and justify (if you haven’t already done so in the Introduction) why your experimental organism is perfect for addressing the issue mentioned above; show experimental equipment and methods (ideally including a photograph of a person doing something); show experimental design (with sample sizes); mention statistical analyses that were used and how they will address hypothesis. Avoid slides with a lot of text. [Approximately 2 minutes, 4 slides].

Results: First mention whether experiment worked (e.g., “90% of the birds survived the brainectomy treatments”) and show some photographs that show interesting or comforting qualitative results (a surviving bird looking content); remind audience of specific hypothesis; present chart of data and explain whether hypothesis is supported; explore data (e.g., “I noticed something unexpected”); end with brief summary slide of main results. [7 min, 4 slides]

Conclusions: Discuss why your results are sound and interesting (convince audience, too); describe relevance of your findings to other published work; state relevance to real organisms in the real world; talk about future directions. If you have more than 1 slide that says, “Conclusions”, rename the earlier ones so that the audience doesn’t actually think you are concluding. [4 min, 3 slides]

Acknowledgements: I hate this slide so don’t include it if possible. Ending a great talk with a laundry list of thank yous will put your audience to sleep and injects a huge void in between your amazing conclusions and the questions from the audience. If you need to thank people, say it on the slides where help was provided. [0 min, 0 slides]

Questions: Leave your conclusion slide up so that your audience can refer to it. Audience member might want you to go back to a particular slide so you should have a handy list of slide numbers so you can quickly jump to that slide: on Powerpoint, type the #, then return. [3 minutes]

[Parting slide]: Optional slide showing “for more information” such as your e-mail address, laboratory web page, and suggestions for further reading (journal articles, books) for those interested. You can leave this slide up as audience leaves and you collect your things.

Note: If you are giving a talk in a 60-minute time slot, aim for a talk that is approximately 40 minutes long (with perhaps 40 slides). What happens to other 20 minutes? You will probably be introduced 4 minutes late, your host will spend up to 5 minutes introducing you, interruptions during your talk with bleed away another 5 minutes, and then you will have 5 minutes at the end of your talk for questions, yielding a seminar that is exactly 59 minutes. Although your host and perhaps several members of the audience may be willing to stay indefinitely to hear you answer questions, try to remember that the majority of your audience will become impatient if you drag the seminar beyond the one hour mark.

Slide layout and design tips

  • Construct slides in landscape orientation whenever possible. This assures that the tops and bottoms of slides fit onto the projection screen and that the view from the back of the room is not obscured by the heads of people sitting up front. If your image is inherently vertical, shrink it so that it fits horizontally.
  • Even with horizontally-positioned slides, try to keep the important information in the top 90% of the slide area. Often the bottoms of slides cannot be seen by people in the back rows because people’s heads are in the way.
  • Use black text on a white background. This strategy makes the task of printing handouts infinitely easier and far less wasteful of toner ink in laser printers and photocopy machines. Using black on white also makes the construction of charts much more straightforward (e.g., you can use the same charts you fussed over for manuscript). Finally, when your background is white you are ensured of at least some light in the lecture room, which is important when you want the audience to be able to see your face or hand movements.
  • If you have only a photograph on a slide, set the background of that slide to black.
  • Adjust font size so that that approximately 10 words fit horizontally (24 point is usually a good size), and line spacing so that only 10 lines would fit per slide. Text that is part of chart should also be 24 point (or close) when the chart is shrunk to fit the slide.
  • Do not use more than 2 or 3 typefaces in a presentation.
  • Your audience will read 100% of the text on a slide, so delete any text that is not essential.
  • Don’t assume that the audience will remember for more than 2 slides what your acronyms stand for, even if you think even a child should know. Remind the audience verbally on every slide or (better) put a subtle “reminder bar” at the bottom of all slides so that even people who slept through the earlier slides will have the ability to follow your presentation if and when they wake up. In fact, avoid using abbreviations if at all possible.
  • Use italics instead of underlining.
  • Avoid using strings of all capital letters in slide titles. Strings of all capitals are difficult to read quickly, and also obscure information inherent in allele names (e.g., Adh) and other nouns that possess mixtures of capitalized and uncapitalized letters (e.g., rDNA, species names). For example, compare “THE FATE OF ADH MUTANTS IN DROSOPHILA MELANOGASTER POPULATION CAGES” and “The fate of Adh mutants in Drosophila melonogaster population cages.”
  • Similarly, do not put slide or figure titles in “title” case. Compare “Effect of Cheap Malt Beverages on Adh Expression in Wild Type and Mutant E. Coli” with “Effect of cheap malt beverages on Adh expression in wild type and mutant E. coli.” In the latter version, a reader can “get” the meaning of italics and capitalization with less brain power.
  • Do not include repeated banners, logos, or backgrounds on your slides. They don’t add any useful information, are visually distracting, and register as pretentious to most people. They are, of course, very popular.
  • Do not use transition fades, bouncing text, or swhooshing noises. Some in the audience might politely chuckle, but most people will cringe.
  • Avoid mixing green and red on a figure. Members of your audience may be red/green colorblind, the most common type of colorblindness. Color deficiencies are rather common among white males, which is sometimes your entire audience in some disciplines. Read up on colorblindness. If you are using Photoshop to tweak figures, the program has color deficiency tools built in.
  • Use figures instead of tables whenever possible.
  • Most graphing applications automatically give your graph a key, but it’s usually clearer to delete it and just label the different elements directly on the chart.
  • For figures created in charting programs and then exported to Powerpoint, make sure that the output fonts and line widths are legible once the image is scaled within Powerpoint. If you keep shrinking your graphs, your audience will squint for a few slides and then give up out of annoyance.
  • If you have a complicated chart, it’s a good idea to add statistics directly onto the chart. For example, if you have conducted an ANOVA and some post-hoc comparison of interest, you might use lines with arrows to indicate which means are significantly different from each other. Next to the line you can say, “means sig. diff.” You can give further details orally.
  • Orient the y-axis label of charts to be horizontal. Vertically-oriented labels are substantially harder to read.
  • Never display two-dimensional data in three dimensions. Reserve that for first grade, USA Today, etc.
  • If you use somebody else’s image, put the photographer’s name on the image. If image is copyrighted (assume it is), don’t ever place your slides online or distribute them digitally.
  • If you overlay text onto a scanned image, apply a shadow to the letters so that the words are legible in both white and dark portions of the figure.

Delivering your talk

  • A big part of giving a presentation is knowing how to connect your computer to the display projector. Don’t assume your host is competent in this regard, so show up early and figure it out. Bring your own connector to ensure you can connect with the projector.
  • Do not rely too heavily on your notes. Relying on pre-written sentences and jokes usually results in forgettable, boring presentations.
  • Do not keep checking to see whether a slide is still there. It almost invariably is. If there is a power outage or your computer falls off the table, then it’s OK to check.
  • Do not read your slides to your audience. The exception is when you think there is somebody visually impaired in the audience. You can ask host about that before your talk.
  • Use a pointer or your finger to orient the audience to specific parts of the slide. E.g., it’s insufficient to say, “As you can see from the slide …”.
  • When using a pointer or your finger, it is best to touch the image on the screen rather than situate the pointer in the projection beam to throw a shadow.
  • A pointer (stick) or a finger is always better than a laser pointer. The dots on lasers are always too small, and only work as cat toys.
  • If you are forced to use a laser pointer, don’t blind people by directing the beam in their eyes.
  • Do not draw more attention to bad slides by apologizing for them.
  • Resist puns, obvious jokes, and overly rehearsed humor. Spontaneous, genuine humor is so much better.
  • Try to minimize your use of OK, like, um, er. People who attend hundreds of talks fixate on these grammatical crutches and become distracted. They will, like, stop respecting the speaker by the end of the seminar.
  • If it is under your control, avoid raising your voice at the end of sentences unless you are asking a question. Although some folks assert that uptalking (upspeaking, Valley talking) is a nuanced and sophisticated way of speaking, the majority of listeners will assume you lack confidence and expertise. For example, many people felt that President George W. Bush tended to uptalk when he didn’t have a particularly strong command of needed facts. Donald Trump does it, too, on occasion. Overeducated, older academics are acutely unforgiving of uptalk. If room is full of tattooed millennials, you’re fine.
  • Etc. is pronounced, “et cetera,” rather than,”Eck cetera.” I’m listing this here because a surprisingly percentage of the population mispronounces this phrase.
  • Adjust your speed or ask whether there are any questions when you notice confused looks.
  • If people in the audience start closing their eyes, speak up and become more dynamic.
  • When responding to questioners, always repeat the questions loudly for the benefit of all.
  • Attempt a response to all questions even when you think there is an audience member who might be able to field it better than you.
  • If you want a blank screen to appear, press the “b” on the keyboard (at least for Powerpoint). It’s a nice way to get people to look at you rather than the screen.
  • If the moderator does not end the question period in a timely fashion, say, “I’m happy to entertain further questions outside; thanks so much for coming.”