How to give a great scientific talk

Created by: Cédric Frenette Dussault, PhD

Last update: April 15 2016


Speaking in public during a symposium, a departmental seminar or during a university class is part of academic life. We seldom realize it, but from thinking about the structure of a talk to actually delivering the talk requires much time and effort if we are to succeed in engaging and efficient communication. This document was created to provide you with tools for improving your public speaking skills and your ability to communicate your scientific research more easily. Speaking in public is more of an art than a science. What is presented here are suggestions rather than rigid rules; these are all ideas that you can integrate (or not) in preparing your next talk. Depending on your personality, some suggestions might be more useful than others. Many aspects of oral communication will be addressed: connecting with an audience, structuring a presentation, designing efficient slides, understanding human aspects that are related to public speaking, and dealing with stress and difficult situations. This document will help you decide HOW to prepare and deliver a talk, but not WHAT to include in a talk. Indeed, you are the only person who can determine the content of your talk. Rather, we will address the way that we present this content.


Enjoyed by some, while feared by (many) others, oral communication can be very efficient in various situations. In research, the main objective of talks is to disseminate new ideas and knowledge. Talks can potentially reach a wider audience than a scientific article could. However, this is not enough. We also have to convince the audience that our research is interesting and that we are worthy of their time (at least during our talk).

Believe it or not, even if you don’t consider yourself as a talented speaker (yet!), you are, in a way, an expert in oral communication! Indeed, you probably have already listened to tens or hundreds of scientific talks by now. You have an intuitive understanding of what makes a great presentation. Some common characteristics of great presentations include a passionate speaker, nicely designed slides, a clear and structured talk, a pleasant and energetic tone of voice, a tempo that is easy to follow, and content that is interesting. A bad talk is just the opposite: a disorganized speaker, who doesn’t make eye contact with the audience, a monotonous tone of voice, overloaded slides, a flow of words that is ridiculously fast, and vapid content. The more awful the presentation is, the less likely the audience will remember.

Unlike written communication, many researchers don’t fully appreciate the value of oral communication. How many times have we sighed at the thought of having to listen to a PowerPoint presentation? Talks should rather be a source of motivation and interest for researchers. The anticipation of being stuck in a room listening to a deadening talk prevents us from focusing on the message. Perpetuating bad presentation habits contributes to the negative perception we might have regarding oral presentations. One major flaw that must be overcome is to consider oral communication as if it were a written communication. Even though the main objective in both cases is to deliver a message, we cannot use the same tactics because they are two distinct communication modes. For example, it is preferable to put less detail into an oral presentation than into a scientific article, because the audience only has one chance to listen to the whole talk.

There is no secret to avoiding a weak presentation: we need to put a lot of effort into it, something most of us underestimate. As a rule-of-thumb, we should invest 1-2 hours per minute of presentation (e.g., 15-30 hours for a 15 minute talk). This may seem excessive, but it is absolutely necessary if we are to control every aspect of an oral communication. This document suggests good practices in constructing a talk. The following aspects will be addressed: connecting with an audience, structuring the talk, starting (and closing) strongly, designing relevant and efficient slides, considering human aspects, and handling stress and difficult situations.

Connecting with an audience

Even though we have put a lot of effort into preparing a talk, various external factors can influence its delivery: the audience, the general objective, and the occasion. This section points to a few elements to consider when preparing a talk.

When delivering a talk, we always have to keep in mind that we need to connect with the audience. This is obvious, but many presenters seem to forget this basic principle. We always give a talk for others, not for ourselves! The audience always has to be of CENTRAL concern: they are the ones who are coming to listen to us and will surely wonder why they should pay attention. A presenter who does not consider this principle will not be able to assess the audience’s level, will try to cover too much content, will include too many irrelevant details and obscure jargon, and won’t bother making eye contact with people.

When preparing a presentation, we must ask ourselves what kind of audience will be in the room. It might seem like an abstract question, but it is very relevant. Of course, we cannot know every person in the room, but we can identify a few characteristics of the majority:

  • Who are these people? Experts in our field of research, scientists from other fields, members of NGOs, members of funding agencies or a general audience?
  • What is their level of knowledge? Are they trained scientists or do they have a low level of scientific knowledge?
  • What is their interest or motivation in listening to your talk? Are they interested in a new methodology or by its potential applications?

These basic questions will help you identify what should be interesting and understandable for the audience. You constantly have to ask yourself if this detail or that element will be interesting to or understood by the audience. This way, it will be easier to connect with the audience. Depending on the audience, the scope and the depth of the talk consequently will have to be adapted. Scope refers to the limits of the talk, whereas depth refers to the complexity and level of details of the talk. For example, imagine yourself giving a talk on evolution. Scope and depth will greatly vary, whether you give your talk to high school kids or to trained geneticists or evolutionary biologists. In the first case, you would probably talk about Darwin and his trip to the Galápagos Islands, illustrate what a gene looks like and explain in broad terms what natural selection is. The scope would be very broad (you would have to give many examples and contextual information on evolution) and the depth would remain relatively shallow (i.e., not too much detail). However, this would be an appropriate talk because you have considered the audience’s level of knowledge and would facilitate understanding of the subject. In the second case, your audience would be expecting something more substantial. A broad background introduction would not be necessary. However, your audience would be expecting novel ideas to be of interest. The scope would be narrower, but the depth would be greater. Therefore, if you have properly identified your audience, you will be able to better define the scope and depth of the talk. This will help maintain the interest of the audience. It is one of the first elements you will have to reflect upon when preparing your talk.

The audience is rarely a homogeneous group. We usually present to a mix of people with varied interests and backgrounds. When this is the case, an appropriate strategy is to vary the complexity and depth of the talk throughout the talk, because the EXPECTATIONS of individuals are not the same. Experts will be interested in complex details and are expecting a presenter to be in full control of the subject. Scientists from other fields have a basis for understanding the talk, but might not be aware of all the subtleties or technological breakthroughs in your field. They might not understand the purpose of the work: this is why it is important, throughout the talk, to highlight the relevance of your work. It is equally important to vulgarize, especially at the start of any section of the talk, because members of the audience could be representatives of governmental agencies, funding agencies, NGOs looking for applied science methodologies or young scientists (i.e., graduate students). Don’t be afraid to talk about SIMPLE or WELL KNOWN principles. Experts won’t be bored as long as each is explained properly. The figure below summarizes a strategy that could be adopted for presenting a talk in front of a mixed audience. We usually start each section with easy-to-grasp ideas and progressively go deeper in complexity. By adopting this strategy, everyone in the audience will be able to get something out of the talk.

Varying the complexity of the talk allows one to reach a broader audience. At the start of a new section, we begin with simple ideas and progress toward more complex ones.

How the audience reacts is also very useful to adapting the talk in real time. Of course, this requires an advanced knowledge of presentation skills, but some cues can suggest if the talk is going well or not. If many people nod and smile, it probably means you’re doing well. In contrast, if people keep yawning or looking at the floor, you have likely completely lost their interest, whether because the talk is too complex or because its tempo is annoying.

The purpose of a talk is not what you want people to remember after it is over. The purpose is broader than that: the general objective of communication. We generally consider four main communication objectives: to inform, to persuade, to inspire, and to entertain. We inform an audience when we transmit information and knowledge. We (try to) persuade an audience when we want people to adhere to our particular position. We inspire an audience to make them dream and think about great ideas. We entertain an audience when the primary objective is to make them laugh. It is important to know the purpose of the talk, because this will dictate the expectations of the audience. Scientific presentations usually cover the objectives related to dissemination of information and persuasion. Scientists are good at informing: they present data, statistics, facts, and logical arguments. But, they are weaker at persuading. Persuasion is utterly important in a scientific talk, because we must absolutely convince people that our research is interesting and that we deserve their attention, even if it is only for a brief period of time.

To improve on the element of persuasion, we need to use a mix of knowledge, emotion, and credibility. These are ancient ideas that are rooted in Aristotle’s Rhetoric. Aristotle recognized three aspects of persuasion: logos, pathos, and ethos. Logos (“reason” in Greek) relates to the logical and rational elements of arguments. Results from an experiment, facts, deductions, and statistics are prime examples of logos. Pathos (“passion” in Greek) relates to emotions to create an emotional connection with the audience. The use of metaphors, anecdotes, and a passionate tone of voice are good examples for improving your pathos. Ethos (“character” in Greek) is related to the credibility, notoriety (in a positive sense, one’s renown or reputation) and confidence of the speaker. Notoriety and credibility are not things that early-career scientists usually possess. A world-renowned scientist has greater notoriety (and thus, greater ethos) than a young scientist. People will tend to accept the former’s arguments more easily. However, by having a good posture, speaking clearly, and by showing that we know a lot about our subject, we can increase our credibility. Referencing the work of recognized scientists can also be of help.

So, by combining elements of logos, pathos, and ethos, we can improve our persuasiveness and increase the probability that the audience agrees with our arguments, while keeping them focused until the end of the talk. Also, its take-home message will be better understood and remembered by the audience. Of course, for this to succeed, the scientific content must be faultless!

Using humour during a talk

Nowhere does it say that a scientific presentation has to be BORING! However, we all have in mind one (or many!) presentation that was nowhere close to engaging and where the end of the talk was seen as deliverance. The previous section has shown us how to make a presentation more interesting and efficient by the use of logos, pathos, and ethos. Humour can also be of aid to spice up a talk. If humour helps you maintain the attention of the audience, emphasize an important element or clarify an idea, then use it. If not, you should ask yourself: why use humour?

A little humour helps in connecting with the audience (i.e., it increases your pathos), but be careful. If you use too much humour, you will lose credibility (i.e., it diminishes your ethos). Furthermore, humour does not mean telling jokes. Humour refers to “the quality of being amusing, comical, funny” (Wiktionary). If you use humour and no one laughs, it will go unnoticed. However, if you tell a joke and no one laughs, this is going to hurt your credibility.

The “safe” types of humour during a scientific talk are topical humour or humour that is related to science in general. A little self-deprecation can sometimes be helpful, because it shows you’re a human being (so, good for the pathos), but do not overuse it, because it will diminish your ethos. Telling an anecdote can be a good idea. Something unexpected can also make people laugh. For the rest, just drop it! Always avoid offensive forms of humour. This is not a Louis C.K. stand-up comedy show, it’s science!

Usually, it is not that difficult to make the audience smile or laugh, because most people want you to deliver a good talk: they are sympathetic to your cause. In other words, humour can be a great addition to a talk. However, if you don’t have much of a sense of humour or if you are not comfortable, you should avoid using humour; otherwise, you will probably make people uncomfortable.

The occasion is the context in which the talk takes place: how formal the event is, the time of day, the allotted time, the size of the audience, and the room where the presentation takes place. All these factors will influence the form of the presentation. For example, we cannot give the exact same talk, depending on the time of day. Early in the morning, people should be more receptive and stay focused for a longer period of time. If your talk is scheduled early, you can include greater complexity in it. In contrast, if your talk is at the end of the day or right after lunch, people will be much less focused, so you should reduce the complexity of the talk. It is the same thing if you are scheduled late on Friday afternoon: people want to leave!

Another example influencing the occasion is allotted time. During a scientific symposium, the duration of talks is usually limited. To respect the time constraint, the structure must be carefully thought out. It is very disrespectful to the audience and other speakers to take more than the allotted time. If the allotted time is not sufficient, it means that the structure of your talk is not adequate. You will have to work on it to fit in. Remember this: you can talk about a topic for two minutes or an hour. It just depends on the occasion!

Structuring the presentation

Building the structure of a talk is one of the most important steps during preparation: a good structure helps to clearly delineate the topic and reduces the risk of losing sight of the main ideas. Good structure also helps the audience to follow the talk effortlessly. Before even thinking about launching PowerPoint, main ideas have to be organized in a clear and logical way. If the audience is able to understand the logical steps between the elements of the talk, the general understanding of its content will be greatly maximized. The presenter has to act like a guide to the audience so they can get the most out of the talk. The presenter must facilitate the understanding of the underlying structure, highlight transitions, and emphasize the important elements of the talk. This allows the audience to understand the logic behind the talk.

Good structure usually requires five basic steps:

  • Identify the purpose
  • Define the audience
  • Determine main ideas
  • Make logical links between ideas
  • Identify transitions and important elements

We already covered the first two steps in the preceding section. The purpose of a scientific presentation is usually to inform and to persuade. The audience is usually a mix of scientists with different levels of knowledge on a given topic, so it is important to vary the complexity of the subject throughout the talk. Defining the audience helps to limit the scope and depth of the talk.

When identifying main ideas, it is not necessary to write them up in a full text; rather, we have to pinpoint the ideas that we need to address during the talk. At this step, it is very important to define what is necessary to the understanding and what is not. Presenters usually have a hard time doing this (i.e., they include too much detail!) and they mistakenly try to address everything that they know during the talk. How not to overload the audience with that?

When ideas have been fully identified, we have to relate them in a logical manner, whether it is by chronological order, by a problem-to-solution format, by grouping similar parts together or by deduction. This is usually the most difficult step, because transitions between the different sections of the talk have to feel natural, i.e., the audience needs to stay focused from one slide to the next. There is no secret recipe for structuring a talk: we have to think about it deeply. Here is one way of structuring a talk: identify a take-home message, a research question that is related to this message, and a striking result linking both elements. The take-home message is the single main idea that you want the audience to remember after the talk. It is a good practice to start by identifying this take-home message, because it helps to limit the scope of the talk. When you feel confident that you have one (not many!) take-home message, the research question should be easy to formulate. This question is the starting point and helps in justifying the relevance of the work that you have done. The question has to be interesting, maybe a little intriguing, for the audience to be interested right from the start. Then, you need to add a striking result to link the question to the take-home message. If you are not able to easily identify such a result, perhaps your question is not quite right; it should be rephrased. Finally, when you have all three elements well-defined, you only need to add some background, some methodological details, and an analysis of the results. Here you go! A simple and efficient structure for your next talk! The following figure summarizes this procedure.

For ideas to be structured properly, you first need to identify the take-home message. This will help you to formulate a research question related to the message. Then, just add a striking result to link the question to the message.

The structure of a scientific talk more or less includes the elements of a written communication (introduction, research hypotheses, methodology, results, and discussion), but we cannot just follow this linear structure. Contrary to the formulation of an article, where the structure is linear, an oral communication often has to go back to repeat important elements of the talk that have already been presented. For example, it is good practice to remind the audience what the research hypotheses were to better appreciate the results and the analysis. This is even more relevant when the presentation includes a description of two experiments. In a scientific article, we would first describe all the methods, after which we would present the results from both experiments, and then the synthesis of the results. During an oral presentation, it is preferable to present in a sequential manner, i.e., present the first experiment (from hypotheses to the discussion of results) and then the second experiment. Of course, we need to include a wider general background and a conclusion that will relate to both experiments. Also, we frequently need to go back during the talk to be sure that the audience got the most out of it.

When the links between the main ideas are clear, we must identify the transition zones and the elements that we will emphasize. Transitions can be stated in many forms: explicitly (e.g., “This concludes section X. Now, let’s have a look at…”), visually (e.g., the slide design of the beginning of a section can be different), or by a pause. Concerning pauses, there is nothing wrong with not talking for a few seconds during a presentation. You may think that the audience will perceive this as you not knowing what to say next, but it is quite the opposite. A pause is like the end of a paragraph in a text: it lets people breathe! The last transition of the talk (i.e., the one just before the conclusion) is very important because it indicates that the end of the talk is coming. If you do a good transition, people should be paying more attention (knowing the end is coming). It is thus more efficient to tell them the take-home message at this particular time.

If we don’t emphasize the key elements, the audience will have a hard time figuring out the important ideas and getting the big picture. We can emphasize elements of a talk by: repeating something many times, stating it explicitly (e.g., “This is important, because…”) or by adding a visual cue on a slide (e.g., changing the font size or colour, adding a red arrow to a graph). The audience, and especially a general audience, needs to be reminded frequently of main ideas in order to understand and remember them. Many presenters will not do this because they don’t want to appear redundant. This is an inaccurate perception, because the audience will generally not know the topic as well as the presenter. So, repeat important elements frequently!

When we talk in front of a non-scientific audience (e.g., during a public lecture or during TV news), we need to think carefully how we structure our thoughts to communicate efficiently. If you give a talk to a general audience in the same way you would with colleagues, the talk will probably be useless. Scientists tend to focus on what is not (yet) known or fully understood. This is what we expect from scientists, but it is inappropriate for a public lecture. A general audience requires more background information and simple explanations of basic science. Examples, reference points, images and metaphors are all useful tools to communicate complex ideas in a simple form. Another common error is trying to cover too much. It is even more difficult for a general audience to discern the important elements of a scientific presentation among a multitude of concepts, ideas and facts. This is why we should, as scientists, hold on to the essential in such a situation. Explicitly stating what is important and repeating it frequently is good practice. Also, the vocabulary must be adapted. It is preferable to stick to simple words, than to use jargon or technical terms. For example, use “caused by humans” instead of “of anthropogenic cause” and “changing through time and space” instead of “spatio-temporal variations”. All these tips will help you communicate better with a general audience.

Not yet convinced? Have a look at press releases or science news from mainstream newspapers. You will notice that the structure is adapted to a non-scientific audience. The following figure (adapted from Physics Today) depicts the concept of inverse structure. The expected structure of a scientific talk is: background details, methods, results, and conclusion. For a general audience, the structure has to be inverted: we must start with what is the most important idea! Then, we explain why it is important, but not from a scientific point of view. We have to put this main idea into context so that the audience can relate it to what they know. This way, people are more able to evaluate concrete impacts of this main idea (whether it is economic, social, political, or ethical) on them, the people around them, or their way of life. Finally, we conclude with some details that bring some precision on what was presented. This structure is advantageous, because people don’t have to wait until the end to get the big picture.

 In order to connect quickly with a non-scientific audience, we must start with the catchy ideas.

Opening (and closing) strongly

The beginning and the end of a presentation are two crucial moments for the presenter and the audience. On one hand, the beginning of the presentation will set the pace for what is to come. A strong start will boost the presenter’s confidence, will arouse the audience’s interest and help them understand where the presenter is heading (and eventually remember the talk better). A good beginning ensures that the audience will stay on track for what is to come. On the other hand, a good conclusion synthesizes the talk and ensures that we end with what is most important before moving on to the questions.

It is very important to start slowly, because the audience has to adapt to the presenter (his personality, his pace, his voice, and the topic). Too often do we see presenters reading their title slide and then moving right into the core of the subject. The audience usually has many questions at the beginning of a talk (who is this person? What does the image on the title slide represent? et cetera) and may be lost right from the start if the presenter starts too fast. A good introduction has to answer the following questions:

  • What is it about?
  • Why is it important?
  • What is necessary to understand?
  • What is the structure of the talk?

What is it about? It seems trivial, but many presenters just don’t state the purpose of the talk explicitly: they show their title slide only a few seconds and read the title quickly. This is unacceptable to the audience. We need to take the time to explain what the talk is going to be about. It is good practice to stay one or two minutes on the title slide, to use a more informative title, and not read the title word for word. It is also important to state the topic explicitly so that the audience does not have false expectations. Concerning the title, it has to be informative, precise, short, and catchy. The title of a talk cannot be in the same format as the title of an article. Sometimes, it is a good idea to formulate the title as a question, because it will give the impression that the presenter will answer it by the end of the talk. It is not recommended that the main result be included in the title. For example, consider the following title (from an article published in Journal of Vegetation Science):

Functional structure of an arid steppe plant community reveals similarities with Grime's C-S-R theory

The title, although informative, is too long and formal; also, it reveals the main result of the study. Here is a modified version that would be more appropriate for an oral presentation:

Is Grime’s C-S-R theory valid in arid ecosystems?

Here, the title is shorter, but still provides enough information for audience members to know what the talk will be about. The interrogative form is also catchier.

Why is this important? Many researchers do not sufficiently evaluate their own work before they start describing what they have done. The audience will wonder why such work is important. If they don’t find an answer quickly, it is a safe bet that they won’t pay attention for the rest of the talk. It can be useful to present an example so that it does not appear too abstract. To catch the audience’s attention, many options are possible: a surprising datum, an anecdote, a rhetorical question, a “shocking” citation or a problem that will be solved during the talk. We need to find something interesting for the audience.

Mentioning what is necessary to understand the talk is essential, especially when we doing a presentation in front of a heterogeneous audience. It is relevant to present a few concepts to facilitate understanding, but it is also a good idea to say what we expect people to already know. Therefore, individuals possessing less knowledge will adjust their expectations. It is also important to present good background information. It helps to understand why the work was carried out.

When the talk is long (30 minutes or more), it is useful to include a mapping slide (i.e., a slide showing the structure of the talk), because people will be able to locate themselves during the talk. Listening to a talk without knowing when will it end can be uncomfortable.

In short, the introduction will be composed of slides (including the first one) creating a contextual background with elements explicitly justifying the importance of the topic, together with a mapping slide, if necessary.

Ending a talk well is essential for the audience to maintain a positive feeling about the talk and the presenter. The conclusion must be the logical final step: the words with which we end the talk must result from has been said. The conclusion must emphasize the take-home message (i.e., what we want the audience to remember). It is not the time to introduce new concepts (which is different from an open-ended question).

The last slide of a presentation is often a one-word slide: “Questions?” or “Thanks!” It is a useless practice, because it does not strengthen the understanding of the topic. A better way of ending is by designing the last slide differently: with the take-home message and a figure supporting the message. This way, the audience always has the important idea right under their eyes. The following figure shows an efficient slide to conclude a talk.

An efficient slide to conclude a talk shows the take-home message. Based on Alley (2013).

Presenters also include an acknowledgement slide at the end of the talk. I suggest that you first present your “take-home message” slide, then put the acknowledgement slide onscreen, and then come back to the “take-home message” slide.

Slide design

Slide design greatly influences the audience’s receptivity to the talk. Design refers to aesthetics but also to the structure and organization of ideas. It is a mix of art and technique. Donald Norman, an emeritus researcher of cognitive sciences at Northwestern University (Evanston, IL), suggests that when something is more beautiful to look at, people will be more inclined to understand its purpose and how it works. This principle is relevant to presentations with visual support: the audience will be more inclined to listen to you if you have nice slides. The contrary is unfortunately true! Nothing causes more boredom than overloaded slides recited in a monotonous voice. The good news is that it is relatively easy to correct this problem.

A bad design mostly stems from default settings of software like PowerPoint. Default settings are wrong for several reasons:

  • The font size of titles is too big and centered (loss of space)
  • The titles are usually too short and uninformative
  • The templates and animations are cheap looking
  • An invitation to add (too much) text in bullet point lists
  • Very few interactions with the audience

Bullet point lists, although commonly used, don’t show causal relations between elements. At best, lists can only show one of three things: 1) the hierarchical structure between elements, 2) their relative importance, or 3) membership in a group. Lists also don’t allow one to highlight efficiently what is important. Lists can be useful from time to time, but they have to be used parsimoniously. Lists must be the exception rather than the norm in a presentation.

Slides that are overloaded with text cause a problem: the passive attitude of the presenter. When a slide is full of text, the presenter’s body will be turned toward the screen instead of facing the audience trying to make a connection. This practice diminishes the presenter’s credibility (i.e., his ethos).

Despite this, we too often still see presentations where bullet point lists keep coming one after another. Everybody knows it is bad practice for the understanding and interest of the audience. However, many presenters still do it (consciously or not) because it is the easy solution. Remember that to deliver an outstanding talk, you need to provide sustained efforts.

Using too many text lists creates a cognitive overload, namely a state where the receiver is deluged with information and cannot process it accordingly. If the presenter just reads the text on the slides, the audience will have three options to follow the talk:

  • Read the text on the slides without listening to the presenter (why have a presenter?)
  • Listen to the presenter without reading the slides (then why show slides?)
  • Switch between the slides and the presenter (often chosen, but highly inefficient)

Regardless of what you choose, the understanding of the talk will be low. Trying to process too many words that are heard and read at the same time results in a more difficult focus on the content, because the area of the brain that processes what we read and the words we hear is the same. A bad slide can be much worse than no slide at all with regard to general understanding. A better practice is to use an image to communicate an idea. Images are processed by another part of the brain, diminishing the risk of cognitive overload. Hence, using images fosters understanding.

To improve slide design, the “Assertion-Evidence” model (AEM) is a good option. The principle of AEM is simple: we combine a short, explicit sentence with a visual proof. The AEM is the brainchild of Pennsylvania State University engineering professor Michael Alley. The AEM was specifically designed to improve the overall quality of scientific presentations.

The image below illustrates the general structure of the AEM. First, we write ONE main sentence (i.e., the assertion) in the upper left corner. The text must be left aligned and preferably hold on one line, but not more than two lines. The idea that is presented must be clear, precise and brief: we avoid vague titles like “Background”, “Results” or “Theory”. The purpose of the short sentence is for the audience to rapidly understand what it is about so they can concentrate on the explanations the presenter gives for the image. It is not necessary to have an excessively large font size. A font size of 28 is generally adequate for people sitting at the back of the room to read. It also takes less space than the PowerPoint default settings. The font should be sans serif because it is easier to read. Then, we add visual proof of what we are asserting: it can be an image, a figure, a diagram, a graph or even a table. This visual proof must be directly related to the sentence at the top of the slide.

Here is the general structure of the "Assertion-Evidence" model.

The AEM is efficient and simple, but requires effort to obtain an interesting result. We must constantly remind ourselves to avoid the temptation of putting too much text on slides. The figure below shows the same slide, before and after using the AEM. The left slide gives the impression that it is there only as a reminder for the presenter. Such practice will inevitably lead the presenter to read the text out loud without explaining the main idea. From the point of view of communication, it is a failure. Remember that the main objective of an oral presentation is to transmit information to an audience. The elements do not show what we wish to present (here, the environmental filtering of species based on functional traits). Also, the image does not facilitate the understanding of the principle: it is more of a distraction! The same slide is presented on the right side after the AEM process. It is much more appropriate for the audience. The sentence is short and explicit, and the diagram clearly illustrates the principle of environmental filtering. The arrow emphasizes that the process is from the regional to the local scale. Such a diagram facilitates understanding: the audience will quickly read the sentence and then focus on the explanations given by the presenter concerning the diagram. No need to switch between the text and the presenter!

A typical example of an inefficient slide. We can greatly improve understanding with the "Assertion-Evidence" model.

To improve the look of your slides, remember the CRAP acronym suggested by Robin Patricia Williams, author of The non-designer’s design book. Four guiding principles unify the organization of a presentation by improving the visual aspect of slides:

  • Contrast
  • Repetition
  • Alignment
  • Proximity

Contrast draws attention on important elements. We can create a contrast by: using another font, modifying font size, using another colour or by using a mix of horizontal and vertical patterns. An efficient contrast is a strong contrast. For example, using size 30 and 32 fonts or using a light green with a slightly darker green are not real contrasts!

Repetition refers to elements of design that are frequently recurring during a talk. For example, using the AEM for slide design is a form of repetition giving coherence and uniformity to the presentation (a good thing for credibility). It can also be a visual element that is used throughout the talk like the background color or a diagram to remind an important element.

Alignment creates a visual link between the elements of a slide. This helps to organize the various elements to create harmony. Aligning the text to the left or positioning several images on an imaginary grid are examples of alignment.

Proximity between elements of a slide helps the audience to quickly identify what is and what is not part of a group. Proximity helps organize information in a coherent way.

By applying these basic principles, the aesthetic value of the presentation increases. Of course, these principles are not absolutes and it can sometimes be adequate to not respect them. However, we must understand them before we can modify them. Here is an example of a bad slide (i.e., not respecting the four principles) with its “corrected” version:

This slide is full of design faults: the images are of varying size, are not aligned and are superimposed randomly. The text is not homogeneous.  This slide is much better: images are the same size and are aligned horizontally. The text has the same format for each image. The result is much more professional.

Presentation software includes graphical options like animations and templates. These are to be avoided! Templates are usually very ugly and animations are cheap looking. In short, they don’t bring much to understanding and it reduces the presenter’s credibility. The only acceptable animation is the “direct appearance” when, for example, we want multiple elements to appear without showing them all at once: we make them appear successively (without any strange animation).

Colours must be used parsimoniously. It can be helpful to emphasize an important element, but we must be careful when choosing the font and the background colour. Many colour combinations make it difficult to read a text (e.g., a red font on yellow background). The best colour combinations that maximize readability on a slide are: 1) black on white, 2) white on black, and 3) white on dark blue. It looks sober but colour-blind people will not have trouble reading. If you want to include more colourful slides, have a look at the colour wheel and the COLOURlovers website to explore colour palettes. You can always improve the aesthetics of a slide, but be sure to preserve its readability.

If you must include images or tables that are derived from an article, pay attention to the image resolution. A simple “copy and paste” is usually not enough to render a clear image on the screen. It is very annoying to hear a presenter say: “We don’t see clearly what I wanted to show you, but…” Always use high-resolution images. To improve the resolution of an image, you have many options:

  • Modify contrast, brightness or transparency settings
  • Use a format that maintains better resolution when enlarging images (e.g., .png instead of .jpeg)
  • Redo the image entirely or partially (in particular, put the title of the y-axis horizontally)
  • Find a better image
  • Don’t use the image if you cannot find one with sufficiently good resolution

If you must present results in a table, don’t put all possible numbers in it, just the ones mandatory for understanding. It can be helpful to include arrows that indicate tendencies. Make sure that numbers are large enough for the audience to read them.

So, by adopting the AEM and respecting some basic design principles, we can maintain the interest of the audience more easily. Remember that slides must remain simple and direct: it is a scientific presentation and not an artistic competition. Slides must hide neither the presenter nor the content!

Human aspects of presentations

Even if your talk is well structured, the slides are neat, and the scientific content is interesting, human aspects of the presenter can still greatly influence the outcome of the talk and the receptivity of the audience. More specifically, delivery – how we express ourselves orally – and body language are key aspects of oral communication that require a great deal of practice. An interesting topic is not sufficient to catch the audience’s attention: you must know how to “be” in front of a group.

Delivery is the main tool with which we communicate our enthusiasm with respect to our research subject. An average speech can be greatly improved with a higher-than-average delivery. In contrast, an excellent speech can be ruined by a poor delivery. The voice controls the delivery. Even though we cannot change our own voice, we can work on certain aspects of it to improve delivery:

  • Volume: the presenter must be certain that the volume of his voice is sufficient so that everybody can hear him. Pay attention not to lower the volume toward the end of a sentence. We can vary the volume to create an effect. For example, we can voluntarily talk in a low voice for a few seconds to force people to pay extra attention. Do not do this for too long, though.
  • Pitch: helps transmit an emotion or feelings. For example, when we ask a question, the pitch changes naturally (the words at the end of the question are higher-pitched). A change in pitch can also be used for humoristic purposes.
  • Rate: the pace at which we pronounce a speech. Rate can also be used for humoristic purposes. We can slow the rate to emphasize an important element.
  • Pauses: we must not hesitate to use pauses at appropriate times, like at the end of a section. It helps to make a transition. Also, using a pause helps not to say “hummm”, a very annoying tic.
  • Pronunciation: the way we say words with a rhythm and sound. For example, saying “nucular” or “artic” instead of “nuclear” or “arctic” are common mispronunciation mistakes. Good pronunciation improves credibility.
  • Articulation: the way we say the different syllables of a word distinctly (e.g. saying “I dunno” vs. “I don’t know”). Like a good pronunciation, good articulation improves credibility.

It is important to vary the various aspects of the voice (except for pronunciation and articulation!) to provide a dynamic delivery that maintains the audience’s interest. Even though you have interesting content, you can lose your audience with a monotonous delivery. Mastering the various aspects of elocution inevitably increases the speaker’s ethos. All these aspects also help in making transitions and emphasizing important elements. Furthermore, showing enthusiasm will make your voice vary naturally without thinking about it much! However, avoid excessive displays of enthusiasm, because it will look forced and unnatural.

Delivery can be improvised, extemporaneous, memorized, or read. Each method can be distinguished from the others by its characteristics:

Method Preparation Credibility Natural Visual Contact Flexibility Risk
Improvised Null +/- Yes +++ ++++ +++
Extemporaneous +++ ++++ Yes +++ +++ +
Memorised ++++ Null No +++ Null +++
Read + ++ No Null Null +
Based on Alley (2013) p. 230

Such methods of delivery are self-explanatory: we improvise an answer to a question, we recite a text by heart, or we read an excerpt from a text. It is possible to use all such methods in the same presentation: a short memorized text for the introduction (some presenters feel safer beginning like this, although I wouldn’t recommend it), an improvised answer to an unexpected question after the talk, the reading of a definition or a citation when the exact wording is important, and an extemporaneous (i.e., semi-improvised) speech for most of the presentation. The extemporaneous method needs a little more explanation to understand it fully. Delivery is said to be extemporaneous when the structure of the talk is well prepared, but the exact words are not known until the speaker pronounces them, i.e., we know the structure (almost) by heart but certainly not the words. Much preparation and practice is required to master the structure of a talk. It is the major disadvantage of the extemporaneous method, but the benefits more than compensate for this inconvenience. A speaker with an extemporaneous delivery is much more credible and natural, in addition to reducing the risks if something does not go as planned. This method also allows the speaker to maintain visual contact with the audience, because there is no need to look at the slides or stop to think about something when talking. The extemporaneous method encourages the use of short and simple sentences, which help to define a clear and coherent speech.

In short, the extemporaneous method is what you should aim for when presenting in front of a group.

The information conveyed by body language – which includes hand gestures, visual contact, body movements and clothing appearance – will unconsciously be processed by the audience to gauge the speaker’s confidence. The body sends many subtle (and not so subtle) signals, which can be used to determine if the speaker is comfortable in front of an audience or if he or she wants to disappear under the carpet. In mastering body language, we can better occupy the space we are allocated on a stage and show confidence.

What to do with your hands? There is no easy answer to this question. Many presenters exhibit their nervousness either by playing with them too much (which can get annoying for the audience) or by “locking” them on a table or lectern (which looks very unnatural). Usually, we use our hands to emphasize an element or to illustrate something. We usually don’t think about it: hands move naturally. However, if this is not natural for you, you should pay attention to your hands and avoid making too many gestures. If that is the case, the “best” solution is to keep your hands together in front of you (but not during the whole talk). This way, you are ready to make small gestures. Also, avoid putting your hands in your pockets, keeping them behind your back, repeating the same gestures again and again, playing with an object, making excessive movements or letting them hang nonchalantly along the body. Also, don’t always leave one hand on the computer ready to change slides: you will look uptight! So, hand gestures must look natural and must be used to explain something.

When presenting in front of a group, visual contact must be maintained most of the time with the audience. Visual contact creates a direct connection between the audience and you. Direct visual contact is usually perceived as a sign of confidence or honesty. In contrast, avoiding eye contact or plainly looking at the floor is usually perceived as a sign of shyness, discomfort, or a lack of transparency. In front of a small group, it is easy to briefly make eye contact with everybody. In front of a large group, a visual scan is necessary to make eye contact with a majority of people. Avoid looking over people’s heads or repeating the same movement (i.e., from left to right like a machine). You must make sincere visual contact for the audience to be interested in your presentation. Avoid turning your back on the audience (a consequence of overloaded slides), because the visual contact is then broken and the speech is not directed toward the audience.

Body movements refer to posture, movement of the whole body, and facial expressions. To demonstrate confidence in front of a group, it is necessary to have a good open structure (i.e., a straight back, no legs or arms crossed). We can walk during a talk, but it will be context-dependent. A speaker will usually stay behind or beside a lectern during a “traditional” talk, allowing few possibilities for movements. During a seminar or a lecture, it is a good idea to move: it will make your presentation livelier. However, do not overuse it (e.g., go back and forth in front of a group), because it might reveal your nervousness. Also, be careful not to swing from one leg to the other. Smiling is a good way to demonstrate confidence and helps reducing nervous tension. A smiling presenter tells the audience that he is happy to be here in front of a group to talk about something that he cares about.

Clothing can be considered as body language. Most people will indirectly be influenced by the presenter’s clothing. You may probably disagree with this: the audience is here to receive some scientific content, not to judge someone’s appearance. It is true, but remember that people see you before they hear you! I am not saying you should wear a suit and tie or a formal skirt, but making a little effort never killed anyone! In scientific environments, the dress code is often not as strict as in other fields (e.g., finances or law). However, it is worth dressing a little better than usual, because people will unconsciously judge our credibility.

Dealing with stress and difficult situations

A major difference between oral and written communication is the level of stress that is involved. Reading an article calmly at home causes no stress at all, but speaking in public will inevitably increase your blood cortisol! Stress has many sources: the questions after the talk, the audience’s receptivity, the anticipation of speaking in public, and being scrutinized by many people at the same time.

The question and answer period can save or destroy a talk! An average talk can be boosted by inspiring and interesting answers to questions from the audience. In contrast, a stunning talk can be burned to ashes if the presenter is not able to formulate coherent and stimulating answers or show his deep understanding of the subject. It is a frequent occurrence to observe highly competent scientists struggling with basic questions. To avoid this, we have to proceed in a proper sequence. First, listen to the question. It is obvious, but it is fundamental. Many people will not pay enough attention to the question being asked; they rather ask themselves (panicking!) what will be asked without properly listening to the question. Instead, concentrate deeply on what is being asked. We often know the answer, but stress will blurry our mind. Ask the person to clarify the question if you are not sure. Then, take time to rephrase the question. This step is useful for two reasons. First, you validate your understanding of the question (e.g., If I understand it properly, [rephrased question], isn’t it?). Secondly, if people at the back of the room did not hear the question, they have another chance of hearing it. Then, we take a few seconds to reorganize our thoughts. There is nothing wrong with taking a few seconds of reflection before answering a question. People in front of a group may feel uncomfortable because of the silence, but this is an erroneous perception. The audience also probably reflects on the question at the same time. Finally, give a coherent and structured answer. It might be possible that you do not have a satisfying answer. If the question is related to the talk, but you don’t know the answer, just say it plainly. Mostly, do not try to come up with a fishy idea, because people will notice! Experts will see this as an opportunity to tear down your credibility. If the question is not directly related to the talk, it is absolutely normal to have no answer. You can still try to make a link between the talk and the question. You can also suggest to the person who asked the question that you could discuss this after the talk if necessary.

A good idea is trying to anticipate questions during preparation. Put some effort into imagining questions that could be asked. This is a relevant exercise, because it helps identify the weaker sections of the talk. Parts of the talk that were less developed also raise questions, so be prepared to address elements that were not discussed directly. You can omit details that are not necessary to the general understanding. If interested, people will ask questions on those details.

If nobody raises his or her hand after the talk, it can be a bit embarrassing. This means that either the subject was very trivial (or uninteresting), so there was no need for questions or the topic was too complex and poorly presented so that nobody understood anything at all. If you put effort into preparing the talk so that it is easily understandable, this should not happen. However, if you present in front of a small group, the audience may need a little more time to “break the ice.” To avoid “questionless” periods, you have two possibilities. First, you can ask a colleague to break the ice by asking the first question. Secondly, you can ask the audience a question. This is less common, but it will create a dynamic interaction between the audience and you. For example, you could ask them what they thought about a complex part of the talk to verify if people understood it well. You could also ask them what their opinion is on a related topic (especially if there is an expert in the room).

If someone takes too much space during the question period, you will have to interrupt him or her nicely to keep control of the situation (but there is usually a moderator for that job). Often, such persons do not have a question for the presenter. They only talk to expose their knowledge or opinion on the subject. Without being rude, ask them to phrase their question more precisely or suggest to them a question they could ask, depending on what they just said. This should be sufficient to make the person sit down. You can thank them for the comment and move on to the next question. The audience will be thankful!

Sometimes, we have to talk in front of people who are not interested or even resistant to the topic. For example, imagine you have to give a talk to land users and the message is that access to a particular area should be restricted because of conservation purposes. If you start by telling them that they will not be able to access the area because it is the habitat of an endangered species, you will never be able to connect with the audience. In such a case, it is advisable to use a deductive approach, i.e., invert the Assertion/Evidence structure we learned earlier. You must present information without disclosing your point of view. The audience will be more able to follow your line of reasoning. If coherent, people should conclude the same thing that you do. People need to understand the logic behind the conclusion. Also, it is necessary to acknowledge their point of view to weigh the pros and cons. All of this will give you extra credibility. Of course, this is not an automatic recipe for success and you will not convince everybody every time, but at least you will have made the effort to understand a different point of view and to win over a “tough” crowd.

The stand-up comedian Jerry Seinfeld once said: “Given a choice, at a funeral most of us would rather be the one in the coffin than the one giving the eulogy.” It is completely normal to feel stressed when speaking in front of a group. Stress and anxiety often arise from unknown situations and from the anticipation we have in such situations:

  • How will my talk go?
  • Will people appreciate it?
  • Will I make it to the end without screwing up?
  • Will I be judged severely for my work?

Don’t fight to eliminate all stress; rather, find a way to use it as energy (i.e., see it as a source of excitement). A little stress helps you perform, but too much stress will paralyze you.

Anticipating a disastrous presentation and negative feedback from the talk will create stress that will keep growing as the time to present approaches. To reduce stress, you have to increase your confidence by working on two aspects: passion and preparation. When you talk in front of a group, you have to be passionate. If this is not the case, ask yourself why you are doing what you are doing! If you are passionate about your topic, you should be ready to put in the necessary effort to succeed. You can be passionate about your research, but if you don’t prepare sufficiently, you will not master your talk and hence, will not be comfortable in front of a group. During preparation, pay attention to the introduction. Stress tends to diminish after you start talking, so it is important to have a catchy and well-structured beginning. Remember that if you show enthusiasm and you know your structure, your credibility will be greatly enhanced (assuming you are ready to put in the necessary effort, i.e., 1-2 hours per minute of talk).

Stephen E. Lucas, the author of The Art of Public Speaking, suggests several tips to deal with stress:

  • Speak in front of audiences: it is taking the bull by the horns! It is not the gentle way (i.e., you may not succeed every time), but this is how you get better in the long term, by acquiring experience and dealing with stress. Taking an oral communication class is a good way to improve your communication skills, acquiring experience and benefiting from the comments of a professional. Practicing in front of colleagues is another way to become more comfortable in front of a group (with a lower level of stress).
  • Visualization and positive thinking: visualization improves presence and elocution. It also creates a sense of familiarity with the talk. The objective is to imagine yourself giving your talk in a confident manner. It also helps breaking the negative thoughts arising from the anticipation that everything will go wrong.
  • Do not expect perfection: most people will not notice your symptoms of stress, so do not worry about looking stressed out in front of an audience! Also, if something does not go as expected, people will not notice because they do not know in advance what you have planned to say or do. Do not draw attention to what has been less successful.
  • Have a good night of sleep: it is worthless to work on your talk until the last minute. Instead, be well rested before your talk.
  • Contract and relax muscles: this helps to lower the adrenaline just before the beginning of your talk. A few minutes before your talk, contract and relax your legs and arms.
  • Avoid coffee and other stimulants: it will increase your level of stress. Also, if you tend to have a “nervous” stomach, do not eat too much before your presentation.


If you still feel stressed and anxious because of an upcoming talk, a respiration exercise, based on cardiac coherence, can help you. Cardiac coherence refers to variation in heart rate. When under stress or angry, the heart beats at a faster and more irregular rate. The brain sends a signal to the heart and the heart adapts itself given the message that is received. The sympathetic (increase in heart rate and respiration, increase in blood cortisol, diminished digestion) and parasympathetic (opposite functions) components of the autonomic nervous system transmit messages to the heart. During stress, the heart receives mixed signals from both systems, causing the heart to function chaotically. The following figure illustrates how heart rate is influenced by state of mind.

The heart rate in a state of cardiac coherence is more regular.

It is well known that the brain, through thoughts and mental images, influences heart rate. What is less known is that the heart can also influence the state of mind (i.e., the brain). This creates a vicious circle where one component influences the other, leading to increased stress. There is a breathing exercise that can help to break this negative feedback loop and to get back to a state of cardiac coherence. The principle is that you have to focus on your breathing and your heart simultaneously. Focusing on your heart and on your breathing prevents you from having negative thoughts (i.e., causing stress). This exercise is not instantaneous: it requires practice to be useful. Check the following article for more information and this website for an audio file explaining the exercise.

A few resources and good ideas

Here are a few good resources to help you prepare a better talk and gain inspiration from others.

Alley, M. (2013). The Craft of Scientific Presentations, 2nd ed. Springer. – This is the book I used to construct the workshop.
Atkinson, C. (2011). Beyond Bullet Points, 3rd ed. Microsoft Press.
Duarte, N. (2008). Slide:ology. O'Reilly Media.
Lebrun, J.L. (2010). When the Scientist Presents. World Scientific Publishing.
Lucas, S.E. (2012). The Art of Public Speaking, 11th ed. McGraw-Hill.
Morgan, S. & Whitener, B. (2006). Speaking about Science. Cambridge University Press.
Tufte, E. (2001). The Visual Display of Quantitative Information, 2nd ed. Graphics Press.
Williams, R. (2014). The Non-Designer's Design Book, 4th ed. Peachpit Press.

Zach Holman's tips for public speaking.
Lucianne Walkowicz's non-talk on giving talks.

How can I get better at structuring a talk?

  • Exercises like pecha kucha (a Japanese word meaning “the sound of conversation”) is a presentation with a fixed structure: 20 slides, each changing automatically every 20 seconds. “My thesis in 3 minutes” is another example of a formative exercise: you have to describe your research project in 3 minutes with only one slide and no accessories. Such exercises force you to consider what is really important in order to understand your research. If you present your subject with these constraints, you are getting better at constructing the structure of a talk.

Where can I find inspiration for my next presentation?

  • Sites like SlideShare and Speaker Deck are a great source of structure and slide design. Personal blogs and TED Talks are also a great source of inspiration.

How can I momentarily block the projection of slides?

  • By pushing W (for white) or B (for black), the screen will become entirely white or black respectively. To come back to the current slide, just press on the same button again.

Ima fraidz to making da miztaks?

  • To have credibility, it is essential to have impeccable visual support (i.e., without errors). Ask someone to verify your slides if you have a poor command of the written language.

Is the preparation of my talk sufficient?

  • Practice in front of friends or colleagues a few times. They should be able to give you constructive feedback.

How can I anticipate broader questions from the audience?

  • You can add extra slides at the end of the presentation in case someone would ask you about a related topic (e.g., an interesting result, methodological details, a conceptual scheme, etc.).

How can I avoid layout problems when using another computer or a different PowerPoint version?

  • Save your presentation as a pdf file and use the “Full screen” mode (Adobe Reader software) or “Diaporama” mode (Preview software on Mac OS). If you have animations, duplicate the relevant slides (i.e., the first slide without the elements that appears and the second one with such elements).

How can I make sure I don’t forget anything important?

  • Use PowerPoint’s “Presenter” mode to see notes, the next slide and the time left.

☐ Show enthusiasm for your subject
☐ Demonstrate the importance of your subject
☐ Avoid any jargon or obscure terminology
☐ Identify the level of the audience
☐ Have a clear take-home message
☐ Create nice looking slides
☐ Respect the allotted time
☐ Practice with friends and colleagues
☐ Bring a water bottle
☐ Have fun!