The Science of Public Speaking

Have you ever been told when preparing for a presentation that you shouldn’t have an outline slide or always have an introduction that is one third the length of total talk?  Perhaps a friend said to you “based on he audience you are speaking to you should …”. Or maybe even your boss said “last time I spoke at that meeting I did this … and it went really well”. Often times we are bombarded with these bits of speaking advice which might be the combination of anecdotal ideas passed from one adviser to the student, or one colleague to the next. Through a hodgepodge of trial and error combined with random bits of advice, we tend to develop a speaking style and stick with it. However, developing a voice in this way can lead a speaker into habits that do not actually help us while on stage.

Think about it, would you ever try to learn a potentially dangerous sport such as rock climbing or scuba diving by only using anecdotal advice with trial and error? So why should we be content to do the same thing in a presentation that can potentially harm our career? Why would we intentionally do something that would effect the impact of our presentation without checking what has actually been researched and confirmed to work? One of the main problems with public speaking is that we fall into a trap of confirmation bias. We try something at a our next presentation and if it goes relatively well then we think “oh that went well” and it becomes part of our repertoire. All the while it is unclear if what we did was the most effective way of communicating to our audience or was did it simply work for only part of the audience. If you are not familiar with confirmation bias watch the video below and see if you can guess the number rule, you may be surprised.

In this post we will look at some examples from research and experiments that demonstrate what works and doesn’t when giving a public talk. This is by no means a comprehensive review of all research done on speaking in public, however it may give you some ideas for your next talk or presentation.

The Introduction

The techniques used in public speaking are often a combination of trial and error, anecdotal advice and methods dating all the way back to the ancient Greeks 1. Unfortunately these techniques are unlikely to be the most efficient way of finding out what works for your audience. The problem is that when speaking in public if the audience misses important parts then the presentation becomes difficult to comprehend.  When scientists try to take a written paper and turn it into a talk, they often forget that a reader can re-read a difficult passage, but an audience member can’t stop you mid sentence and ask you to repeat the material (unless you are teaching a class). Therefore, getting the audience’s attention in the beginning of the talk is crucial 1.

There are many ways to begin a talk, but in general research shows that a clear easy to understand introduction will increase audience retention by peaking interest 1. There are several options to use here, but some of the more common ways are; telling an anecdote, posing a question, or simply a calling attention to an important idea (e.g. Forest fires effect not only wild lands but also threaten homes and citizens, our home town is prone to forest fires). If you are starting with an outline slide and using the words “today I will talk about Forest Fires, show our experiment, discuss results, etc” you are damaging the ability of the audience to retain information about your work. Introductions make audiences more willing to listen, think more highly of the speaker, and understand the material better 1. In general if you peak the interest of the audience, they will pay more attention to you and it will increase the retention of the material 2. Your audience will respond differently to different opening techniques but this can be predicted if you plan ahead. Speaking to a crowd of scientist may require one type of introduction while speaking to the general public requires something different. Plan ahead and tailor your talk around not only your material but also your audience. 

Speaking Rhythm, Repetition,  and Body Language

Adding the dramatic pause to your presentations can help the audience retain more information, however it needs to be used in conjunction with other methods 2. For example using the correct body language has been shown to be about as effective as dramatic pauses when speaking 2. Additionally Repeating yourself in a presentation will increase retention among your audience, however don’t overdo it. Research has shown that if you repeat to many times your audience may actually retain information less well over time. The most effective method has been shown to be repetition in the logical places that the audience might expect, like the beginning, middle and end of your talk 2. In general your presentation will benefit from the correct amount of pauses, repetition and gestures.

"Police Line" Tape

Becoming an Authority Figure

There is a distinct advantage when someone is perceived as an authority figure. If you are not already one in your own field, then adding a part where you establish authority over the subject matter will help the audience stay interested. In an experiment setup by 4, an audience that heard a “professor” speak, and showed a significantly greater percentage of change in their opinion toward the “professor’s” thesis than those who heard a “student” speak. When speaking as an authority figure you should try to avoid being biased and only presenting one side of the argument or research question. Acknowledging “both sides” produces significantly higher retention than does only presenting “one side” of the story 4. From the beginning it is in your best interest to try to establish yourself as an authority on the subject and enhance your credibility. This won’t necessarily make people more willing to listen alone but when combined with other techniques such as a solid introduction it is conducive to an audience that comprehends more of your material 1.

Effective Use of Humor

Some people are naturally funny and will likely draw large crowds when they speak. Humor can be used to add to an already fun or interesting topic, or it can take something dull and boring, making it more enjoyable for the audience. Research has shown that if your material is very dry that adding humor to your next presentation may make the audience find the talk more interesting, but may not dramatically increase the audience retention 3. It is probably best to use your own judgement and common sense as to when to inject a joke to lighten the mood during the dry and boring parts. Just remember that humor alone cannot be relied upon to keep the audience completely attentive and retain all the important information from your work.

A Final Consideration

When speaking in public the audience can be brutal in judging the speaker even in the first few minutes. It only takes a short while for the audience to judge if the subject is boring or the speaker is unprofessional, and become less receptive to the overall message 1. Many contemporary scholars believe that science is not communicated effectively to the general public 5. The problem is that understanding who you are speaking to is tricky, and requires that the speaker have take time to also consider the audience composition. When conveying complicated material (in science communication for example) the speaker must be comfortable understanding scientific findings, must be sophisticated in the translation of these findings into simple language, and make it all accessible to the entire audience 5. Communicating science does not necessarily mean transmission of the scientific findings themselves directly, since research has shown that an audience will often fell the need to voluntarily research further into the material presented 6. It is important not to forget that when speaking on stage we become storytellers to the audience. Storytelling plays as significant a role in the future of science communication just as it has done in the past transmitting vast amounts of human knowledge 6.


  1. Andeweg, B. A., de Jong, J. C., & Hoeken, H. (1998). “May I have your attention?”;: Exordial techniques in informative oral presentations. Technical Communication Quarterly, 7(3), 271-284.
  2. Ehrensberger, R. (1945). An experimental study of the relative effectiveness of certain forms of emphasis in public speaking. Communications Monographs, 12(1), 94-111.
  3. Gruner, C. R. (1970). The effect of humor in dull and interesting informative speeches.
  4. Paulson, S. F. (1954). The effects of the prestige of the speaker and acknowledgment of opposing arguments on audience retention and shift of opinion∗. Communications Monographs, 21(4), 267-271.
  5. Treise, D., & Weigold, M. F. (2002). Advancing Science Communication A Survey of Science Communicators. Science Communication, 23(3), 310-322.
  6. Veríssimo, D., & Pais, M. P. (2014). Conservation beyond science: scientists as storytellers. Journal of Threatened Taxa, 6(12), 6529-6533.

Leave a Reply

Your email address will not be published. Required fields are marked *