Animate using motion path or action builds


Motion Path animation (Apple Keynote)
Animations with Motion paths (link to the video demonstration)

The oral presentation surpasses the journal paper in many respects, but surely, one of the key differentiators has to be the use of animation to explain. A method comes alive on your screen whereas, on paper, it is mummified, embalmed in the  sarcophagus of a diagram. Microsoft PowerPoint and Apple Keynote enable you to put objects in motion. Trace a linear or curved path and have the object follow that path at a speed, acceleration and deceleration set by you. Decide on an angle and have the object rotate to that angle, fix a size and have the object grow or shrink to that size, set a transparency level and have the object gain opacity or transparency. Combine all these actions together (yes, it takes the skills of a choreographer sometimes), and you can resuscitate the dead… diagram, that is:)

A word of warning: Animations take time to build. It is not unusual to spend  an hour on a 30 second animation. But the results are beyond your wildest expectations. You, the presenter, will be a cut above the rest.

Use animations in the following circumstances:

Whenever you feel like using your hands and making gestures to explain something (this does not apply to Italians who feel like that all the time).

Whenever you want to describe the path followed by something in motion (an ion, electron, light, virus,…) through something else (a porous barrier, a membrane, a conductor, an optic fibre,…) over time, or over a number of sequential steps.

Whenever you want to guide the eyes of the audience to a succession of specific places on the screen without using the distracting laser pointer.

Whenever you want to represent objects whose speed, acceleration, shape, action, colour, or transparency changes over time or when these objects interact with other objects.

Whenever else you deem necessary to explain something faster, more clearly, or more interestingly.

Do not use animations in the following circumstances:

You have not yet mastered PowerPoint Motion Path techniques, or Keynote’s actions.

When you have no good reason to use animation (gratuitous), but you just like it, and want to work for Disney or  Pixar.

Learning about your audience from where people sit

I want to sit as near to the stage as possible when I watch an opera or  a broadway show or the newest show at the Cirque du Soleil. Naturally, everyone want to sit there, so the most expensive seats are the front seats. You hear better, see better, and feel closer to the actors.

Now where do you sit in a movie theater? If you are like me, you sit in the center of the middle row, but if your intent is not to watch the movie, you may possibly sit in the back row. The back row is more secluded, whereas immersion into the story is better at the center in the middle rows where there is no need to get up as people fill the row.

Where do you sit in a restaurant? Again, depending on your purpose, and the restaurant location you may prefer a private alcove or sit at a window table from where to admire the beautiful landscape or the passerby.

Where do you sit in church? Late comer, not sure you want to be there? At the back, of course. Prideful today or filled with zeal and angelic fire? Front row, same as the preacher.

Note that where you wish to sit reflects your need and your intent. But it also reflects the quality of the “performer”. Where do you sit in a breakout room when you attend a scientific talk?  Let me guess… At the back or in the aisles, ready to make a fast exit should the presenter not meet your expectations and bore you or flummox you with jargon-laden text heavy slides. However, if the topic is of great interest to you, or if you know the presenter is of the captivating sort, you will probably sit in one of the front rows.

The presenter learns much from observing where the audience sits. Who to network with (front rows) – who to win over with a great start so that they do not make a run for the exit door in the first three minutes (aisle rows) – who to ignore because they just came to find a place to rest or to busy themselves with matters unrelated to the talk (back rows).



Flickr – Benson Kua . Empty seats

Automatic Line Break on the Title Slide: a readability breaker

Do not let your presentation software break compound nouns across lines. Noun-preceded modifiers should be on the same line. In the following example, it makes little sense to let PowerPoint or Keynote automatically place p53 and GADD45 on two separate lines because it makes your title unclear : “A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia“. At first reading, the reader thinks each line makes a separate point.

“A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia” is unambiguous.

How is one to avoid such incongruous line breaks? You have the easy and the hard choices.


1) Insert a carriage return at the appropriate place to avoid bad line breaks.  2) Reduce or increase the font size until the bad line break disappears. If it does not, try the first choice.
3) Increase or decrease the size of the text box by dragging its handles until the troublesome line break disappears.


1) Insert a hard space between the words that should remain on the same line as “cell cycle checkpoint pathway” in the example title. On my Mac, the hard break character in Microsoft PowerPoint is Option+Shift+Space.  2) Those who can’t find the hard space (also known as the non-breaking space), can fill the rest of the line with as many characters as necessary until the line wraps and give these additional characters the color of the background to make them disappear.
3) Rewrite your title and avoid placing more than two modifiers in front of a noun by adding a preposition to break the long chain of words into shorter segments. If we tried to do this on the sample title

“a mammalian cell cycle checkpoint pathway”

we would run into trouble. Adjectives like mammalian are not usually a problem, they can be separated from the noun they qualify at little readability cost. However, there is no such thing as a mammalian cycle, or a mammalian checkpoint; Mammalian belongs to cell. Long nominal chains like “cell cycle checkpoint pathway” or “checkpoint pathway” cannot be separated. For the uninitiated, a long modified noun is not easy to decode. Does “checkpoint” belong to cell cycle or to pathway? An expert would know, but not every reader is as expert as the writer. A preposition would clarify: “Checkpoint pathway of the cell cycle”, or “Pathway of the cell cycle checkpoint”, whichever represents the correct meaning. And “of” may not even be the right preposition!

The perfect presentation start: Make your work relevant to the audience

I love watching Ted Talks. I often analyse them with the scientists who attend the scientific presentation class. One thing TED presenters do extremely well is to bring in the audience into their world at the beginning of their talk. Joe Landolina, in an excellent presentation on his wound-healing invention, starts with the following words: “I want you guys to imagine that you are a soldier running through the battlefield. Now you are shot in the leg by a bullet severing your femoral artery. Now this is extremely traumatic and can kill you in less than three minutes.” Behind him on the gigantic screen is the picture of soldiers walking away at sunset, followed by the image of a soldier on the ground with a leg wound. The images help your imagination. You are the first person witness to a traumatic life-threatening event.

I can hear some of you scientists already objecting! “Our scientific work is not traumatic. We rarely get to use emotions to pull in the audience into our topic.” Yet the presentation is about a polymeric gel that temporarily binds with the extracellular matrix scaffolding to help seal and vascularize a wound. The presentation includes analogies (forest canopy, etc.) and an animation to bridge the knowledge gap on the extracellular matrix. In this case, bringing the audience into the talk was through the application of the gel the scientist created. But you could bring the audience in through the context of your work.

I remember a presentation which took place on June 13 2016, the day England decided to quit the European Community – Brexit day. The presentation was about the impact of  political uncertainty on mergers and acquisitions. Instead of relating the political uncertainly to Brexit, the presenter talked about the 2017 US elections – forgetting all about the traumatic event that happened that day! I also remember that other presentation on Fluorescent GFP tag the very day after its inventor, Roger Tsien, the nobel laureate, passed away. The presenter made no mention of the fact!

Finding a relationship between your topic and what is in the eye of the media is one of the surest way to interest your audience and make your topic relevant.

To conclude: You want attention? Make your topic as close as possible to common concerns.



(TDD) Test-Driven Development – its use in scientific presentations

How does one know that everything is going to be fine “on the night”, or at least on the big day of our presentation? Of course, one could cross fingers – but should the index finger be over the middle finger or the opposite  🙂 One could rehearse, and rehearse, and rehearse as proposed here – this works but can one rehearse the unexpected? The rehearsal trap is so pernicious!

Do you know the meaning of the TDD acronym? If you do, you are a leading edge programmer.

“In Test-Driven Development, each new feature begins with writing a test. […] it makes the developer focus on the requirements before writing the code.” (Wikipedia)

 How does that wonderful concept applies to scientific presentations?

Continue reading “(TDD) Test-Driven Development – its use in scientific presentations”

What can the scientist who presents learn from Herbert Simon (Part 2)

I heard Nobel Laureate Herbert A. Simon speak at the end of last century (it’s not that long ago) at a conference in San Jose California on future trends. His insights on our information age will forever ring true.

“What information consumes is rather obvious: it consumes the attention of its recipients. Hence, a wealth of information creates a poverty of attention and a need to allocate that attention efficiently among the overabundance of information sources that might consume it.”

Who bears the cost of information overload? Continue reading “What can the scientist who presents learn from Herbert Simon (Part 2)”

Using images in presentations – the legal issues

First of all, I am not a lawyer. Now that I have completely disqualified myself, and warned you that any information given hereafter may or may not be true in a given country at a given time for given people in given settings for given tasks, I can now broach the subject.

The other day I was looking at a medical clipart site which contained ancient black and white clipart images which had obviously fallen out of the copyright realm and were in the public domain – IT WAS NOT. Why? The people who had scanned the black and white pictures from ancient manuals in the public domain, considered that the work of scanning, cleaning the drawing (removing the aged paper color to make it white again), cropping the final art and giving it the clipart resolution was considered DERIVATIVE WORKS of a public domain image. In other words, if your aim is education, feel free to use it, but if you use it for a commercial presentation – find the book at your national library and scan it yourself :).

And now for another surprise. You visit an art gallery where a 1789 painting (surely no copyright issue here, right?) attracts your attention and you take a high resolution photo which you use on your slide and distribute or make available to others. Understand that the law in the US and in the UK is different. In the US, you could do that without problem. In the UK, the art gallery could make trouble for you unless you only use a low resolution image.

In this blog I use images that are under CC licence (Creative Commons). If you are not familiar with Creative Commons, STOP whatever you are doing and visit From that page, you have access to the images that you can reuse under very well defined conditions. For example, I selected the button “Use for commercial purposes”, and deselected the button “modify, adapt or build upon”,  clicked on the button “Flickr”, selected “the Commons” in the menu on the left of the search line and then typed “eye” in the search window. I found a great image named “Elod-Eye” by Frederic Dupont (a.k.a darkpatator). Then scrowling down the page, at the bottom right,  I found the license type, in this case “Some rights reserved”. Clicking on the licence name in grey takes you to the page Some rights reserved which explains what are these rights. You can then use that picture on your slide according to the stated rights.Here are several sites where you can find public domain images: and also the images of the British Library and of course the huge Flickr internet archive book images


There are other issues of course. The first one is the display of recognizable people on an image. Each one of us has “personality rights“, which include the right to control the commercial ( and even non commercial) use of our image and likeness. They vary from country to country, and from State to State. So even if you yourself took the photo, as long as it contains a recognizable person, before using that photo for a presentation, it would be wise to make sure that this person has given you permission to use that photo in a presentation (there are release forms available online that you can base your form on).

Now for the case where your slide features diagrams from other published papers (say as background information), or images from a webpage, should you mention the source of the diagram or of the web-image on your slide under the image or diagram? ABSOLUTELY. If it is from a scientific journal,  you could write the last name of the author and initials, the year of publication, and the abbreviated journal name, in readable font size. If it is from a website, the URL of the site. You would not want to be accused of plagiarism in a public forum, now would you?

By Jean-luc lebrun

Presentation traps 12 – The trap of the introduction slide

By Jean-luc lebrun

You are certainly familiar with scientific presentation slides that have all the structural signs of the scientific paper they were extracted from (same headings, same figures, etc). After the title slide, you will often found a slide with the title “introduction”, “outline”, “motivation” or  “aims”. Anything wrong?

What is the function of that slide?

Yes, its function is to introduce… but not only that. Its function is make sure that the people sitting at the back of the room listen to your whole presentation. The back-sitters are migratory scientists eager to take flight when the temperature you maintain around your topic drops below hibernation temperatures. And they start packing as soon as they see the frigid outline/motivation/aim/introduction slide. After all, it is faster to read your paper than to listen to it (twice as fast, in fact). So the role of this introduction slide is to intrigue, to hook, to captivate the audience by asking a question that becomes the question of everyone in the audience, a question that will keep everyone awake and attentive for the next twenty minutes while you unravel and answer it. Put your question to your audience in a visual form. Make your motivation their motivation, your problem, their problem. Then, when you reveal your solution, it will be theirs also; what satisfied you will satisfy them.

Background knowledge is rarely captivating. You need better than that to hook your audience. Tell a story, give a compelling example, make whatever you are doing essential to THEIR lives. Do not state commonplace facts already known by all in attendance. State the surprise, the novelty, the anguish, the reward… Forget about the conventional wisdom which is foolishness: it is not necessary to give an outline for any talk that is less than half an hour. Would you greet the friend that comes to your home by keeping him one minute at the doorstep explaining the various rooms he is about to go through before sitting down? Or will you just open the door and let the perfume of that scrumptious cake you baked for her capture her pheromone receptors?

The introductory slide is a teaser tightly connected to your title and your purpose. It entices the audience, and keeps the people in the audience in their seat by riveting their attention on you, and your mouth watering topic. And, oh-by-the-way, The hook slide has no title. Save the electronic ink it would require for your visual.

Image Flickr; author: LunnaDRimmel

Keep what the audience sees in sync with your speech

Take it from me, as a presenter, if you don’t sync, you do not exist. Have you ever wondered why the audience does not pay attention to you, but only has eyes for the beloved PowerPoint slide? Feel like a jealous lover? It’s apple of the eye for PowerPoint and tin ear for you!

When that happens, it is simply because you are not keeping what the audience sees in sync with your speech, in other words, the audience is suffering from a chronic case of divided attention. We, human folks, are not very good at doing two things at once when our senses are pulling us in different directions.


The cure to the presentation problem is actually straightforward – and it’s not “Present now and drink later to drown your sorrow!”

1) Guide the eyes to what you describe.

Discourage forward reading and re-reading.


Point, circle, color what you describe, remove highlights after description.

Move the pointing object, or ask the audience to track an object moving through the static slide .

2) Take the attention away from the screen when the screen does not support your talk.

Blank the screen (B-Key or black slide).

And finally, move away from your position, change your intonation, stop talking.

Our brain is actively engaged in determining what changes from one moment to another. It pays attention to what changes. Motion of the presenter is perceived at the same level as any change on the screen. Therefore, move from your base position, use gestures. A new voice pitch or added intonation is also perceived as change by the ear. Silence is perceived as change just as effectively.

By Jean-luc Lebrun

Image source: Flickr,Author photo 1:  “pedestrian photography”; photo 2: “Colin Purrington”

From Presenter Ghost to Presenter Host

To turn a host into a ghost, just add the letter G. And to turn the presenter host into a presenter ghost, just add a computer and PowerPoint. When you invite other scientists to come and listen to you via the proxy of conference programs, you become a host, and the scientists who turn up for your talk are your guests. Yet, unbeknownst to you, you are sharing the limelight with a formidable co-host whose dream is to turn you into a ghost, a shadow of your own self. This co-host is the computer connected to the towering bright screen overhanging your lilliputian silhouette, a screen that plunges your face into semi darkness as effectively as the sun creates a moon shadow.

As host, you have to keep your giant co-host in its proper place: that of a servant, discreet and supportive. And for that, you have to be seen.

1) Keep the room lights full on, turning them down ONLY when a slide requires darkness for readability (fluorescent marker in protein tags for example). But for that, you will need to lose the dark slide background and go for the classic white background on which black letters stand out better even when the stage is lit. Keeping the lights on reduces the contrast between the screen and you, thus enabling you to stand out more.

2) Everything that moves on the screen attracts attention away from you. Therefore, remove these gratuitous animated gif files that constantly move on the screen, or the loop in looping video clips that mesmerize the audience and remove you from the apple of their eyes.

3) Everything that moves on the stage attracts attention away from the screen. Therefore, do not turn into a pillar of salt. Move, use gestures.

4) Disable your co-host out for at least twenty seconds, with a black slide or a B-Key; and enjoy the renewed eye-contact with the audience while your co-host is blindfolded and muted.

5) Keep constant eye-contact with the audience, but for that you will need to be so well prepared that you know without looking at the screen what appears on it as you click the advance button on your presentation remote. The people in the audience do not look at a host who does not look at them.

6) Vary your voice intonation and volume, they act as audio gestures, re-centering on you the attention of the audience.

7) Reduce the amount of information on each slide. When people have read a slide, having nothing else to read, they have no choice but lay their eyes back on you!

8 ) And for Pete’s sake, do not let the computer thank the audience and announce the Q&A. You are the host, aren’t you!!!

9) Do not stand behind the lectern. You want your whole body to be seen, not just a truncated version of you. Wear a wireless mike and use a presentation remote to be able to move away from your computer.

10) Be pleasant to look at :), not an disheveled eye sore.

By Jean-luc Lebrun

Image source: Flickr. R Motti. XXVII

027 Speech first slides second

Dr Rao Machiraju, in the final part of the interview, suggests a provocative way to prepare a scientific talk…. the augmented speech. Be ready for Rao’s final one liner which is so good,  it should be carved in stone, or at least printed on a T-Shirt!

Image Flickr; Author Smilla4

What can the scientist who presents learn from Antoine de St Exupery

“It seems that perfection is reached, not when there is nothing left to add, but when there is nothing left to take away.”

(Terre Des Hommes, Chapter 4)

This is so applicable to scientific presentations. The starting point of a presentation is usually the scientific paper. Selection of the contents of the presentation is, for most, a subtractive process, the result of chiseling out and polishing of material until it looks deceptively natural, having “the elemental purity of the contours of a shoulder or a breast”, writes St Exupery.

The presenter knows that naturalness has come to a slide when side details that clothe the basic idea have been removed; when diagrams, transmuted from high density lead to light density aluminum, still conduct information to our resistive brains; when the eye and the ear, in total harmony, never divorce or separate because the visual life of any projected object, as it makes its way to our brain, never extends beyond its spoken life. Once the visual’s verbal amplification comes to an end, the clarity of the visual content is such that lingering on the visual is not required unless the presenter encourages further contemplation to give nascent ideas time to germinate.

What gives an outline that natural shape? It is the title of your talk. Let its invisible hand guide your chisel.

By Jean-luc Lebrun

Source Flickr. Author bmhkim

Presentation traps 8 – the knowledge trap

“And here, you see…” These are the famous words that ring hollow to the blind. But the lack of knowledge leaves us just as blind – a temporary type of blindness, assuredly, but blindness nevertheless. For knowledge only lights up the world of the expert rambling along, finger pointing to familiar shapes on the laptop screen, and occasionally on the projector screen (the one everybody sees) whilst most of us in the audience, eyes stretched in front of us, grope in the dark and clutch at shadows.

The trap is common: the presenter expects all of us in the audience to be experts. We feel like the little Marys and Johnnys in primary school reading the story of the house cat. “The cat ate a mouse”, the story goes. “The rodent was fat.” At this precise moment, we all got the idea that the cat was a rodent – after all, it just ate a mouse!  The world has not changed that much for the scientist since primary school; the story just got a little more complex. “The felis catus ate a murine commensal. The mus musculus’s BMI exceeded that of a standard murinae.” At least scientists won’t mistake the mus musculus for a felis catus… or will they?

My advice to you is to look at the contents of ALL your slides from the point of view of ALL the people the title of your talk attracted. Who are they? What do they want from you? The answer is not a simple “they want to know about my contribution.” To know what they want, look at your title. Each search keyword in your title acts as a magnet attracting the expert AND the non-expert. For each keyword, the audience expects you to give new information AND background information. Redo and simplify your slides to remove the knowledge gap between you and the non-experts. And move your tough expert slides after your conclusion slide, ready to answer the experts’ questions during your Q&A.

By Jean-luc Lebrun

Image flickr; Author Dnudson

The Acknowledgment Slide

If you are like most scientists, chances are that you will place the acknowledgment slide at the end of your presentation. But if you watch one of the Hollywood award events, or attend a Nobel laureate award presentation, chances are you will hear the acknowledgments at the very beginning of the acceptance speech. Why? Because the people you recognize as being part of your success are in the room, and if you fail to mention them as in “and others too many to mention”, chances are that the ones who are in the “too many” category will be miffed or downright offended.

In a scientific talk, the presenter acknowledges 1) the corporations which funded the research (they may have a representative in the room) and 2) the individuals who had a large part to play in the success of the research (their friends may be in the room). But where should the acknowledgments be? At the beginning or at the end of the presentation? On the title slide or on their own acknowledgment slide? And how long is the list of people/organizations recognized?

Let’s start with the first question: Where does one put the acknowledgment slide?

If you were to place it at the end, as in the scrolling credits of any movie, chances are the audience will have switched off or left the room by the time the credits roll; Or chances are you will go over time in your presentation and will have to skip the acknowledgment slide. Whichever way you look at it, the perspective is bleak. Take a clue from Hollywood. The great actors demand that their names be displayed AT THE BEGINNING of the movie for a duration and a font size that match their most excellent performance (and acting fee). Fortunately, your faceless research sponsors do not demand such status. And they will be quite happy to let you mention them through the use of a Logo – so you don’t have to remember their last name. Your collaborators, however, or those who helped you hit the mark, have a name, and a face. So you have a choice: use one or the other – but not both – and don’t add an aureole around your bosses’ heads, or add glow around their names. Acknowledgments are not an ego building or a sanctification thing. They serve two functions: 1) recognize and honor the work of your collaborators, and 2) establish credibility in you and your work. Think of it this way: why should prestigious donors partake of their money or the taxpayers’ money to fund you and your work if both you and your work are not worth it!

But how long is the list?

If you are like me, you love yet you hate these song request radio programs where popular songs are played only after a long list of thanks to the caring husband, the faultless children, the exquisite grandparents, the perfect neighbors, the pet parakeet, and the fire department and rescue squad – notwithstanding the radio host in the studio, the audio technician in the soundproof room, and the janitor  who cleans up the ashtrays and turns off the lights. Therefore, be brief and instead of mentioning individual names, use collective names to mention “many people” as in “our team”, or “our department”. A photo of the team flashed briefly does wonders to establish you as a team player, and an honest and fair scientist. Those mentioned by name in writing on the title slide are the co-authors of the paper you are presenting – and only them.

So where exactly do you place the acknowledgments?

Either with Logos and Names on the title slide, which tends to stay on the screen for a while at the beginning of the talk, or briefly and using photos, on the slide that follows the title slide.

Oh, and by the way… The BIG THANK YOU slide… Get rid of it! Don’t let the computer take over. You are the presenter.

By Jean-luc Lebrun


Photos: Flickr. Authors: image on top- Mangee

Nothing reveals personal expertise better than questions; therefore,…

Image source: Flickr; Author :Tintin44

They were certain that their expertise would be seen through the high density of information on their slides. They were certain that removing an ounce of proof would be like losing a pound of flesh – a tragedy of Shakespearian dimension. They were certain that confidence displayed would translate into expertise perceived. But their certainties were rational myths.

Slides never proved expertise. 1) Slides prepared by an expert may be presented by a non-expert. 2) Junior scientists not yet familiar with a field of research tend to densely pack facts and points on slides so as not to forget (mentioning) them. The more a presentation looks like a condensed version of a paper (for example by keeping the reference to figures used, or by packing on one slide all the visuals illustrating a point), the more the presenter may reveal lack of expertise. Why? An expert’s understanding of a problem is such that, what is principal claim, what is central proof, and what is key impact, are easily identified. An expert can easily unpack a slide; A non-expert can’t.

Confidence never proved expertise. 1) Multiple rehearsals give most presenters a higher level of confidence which leads to a smoother delivery – regardless on their level of expertise in the presented topic. 2) Over-confidence often marks ignorance. You only know that you don’t know when you know enough. Superficial knowledge may give you undue confidence. 3) Lack of scientific expertise cannot be inferred from the nervousness of a presenter.

Correct answers to unprepared questions prove personal expertise. It is through the Q&A following a slide presentation that the  presenter reveals the extent of his or her expertise. The unpredictability of questions and the presence of other experts in attendance guarantee it – for indeed, it takes an expert to identify an expert.

In conclusion, do not try to establish your expertise through packed slides. Let it shine during the Q&A session. But for that, you need to make sure that you have time left to answer questions! Indeed, finish slightly early so that you have more Q&A time. And when one asks a question, do not answer at length, thus wasting the opportunity to be asked more expertise-revealing questions, and to identify other scientists interested in your work.

Oh, and one last thing… An expert never answers a question with “I think”. An experts knows.

I Think, Therefore I Am…. Not an Expert (non-existentialist ending to the famous René Descartes quote)

By Jean-luc Lebrun


Rules of thumb for presentations – how good are they?

Photo Flickr – by Lintmachine

People like formulas. They are expedient rules of thumb that guard against dangerous extremes. “Plan for one minute  and a half per slide”, some say, “and never put more than 5 bullets point and more than 5 words per bullet point”. Under these rules lie hidden assumptions about people’s attention span, prior knowledge of the presented topic, text readability, number of clicks needed to go through the material on the slide, audience interactivity, and more!  Presenters could be fooled into thinking that as long as these rules of thumb are followed, their presentation will be fine.

Rule of thumb #1: “Plan for one and a half minute per slide” is about as silly as telling a writer “Plan for chapters with 20 pages”. What is the purpose of this rule? It prevents presenters from putting so much information on one slide that to cover it would take more than 90 seconds. It also prevents boredom: people don’t generally like to stare at the same information for a long time. They get bored because they can read faster than the presenter can speak. Spending three minutes explaining each bullet point is as effective as administering a sleeping pill. What is important here is visual interest, not screen-time. A 30 second slide that gathers interest is fine. A two minute slide that exploits a particularly fruitful visual is fine so long as interest is maintained (let the audience be the judge of that through their questions). A slide that dynamically reveals and removes information through the use of layers can last a very long time, and it’s perfectly fine.

Rule of thumb #2: “Use not more than 5 lines and 5 words per line” (some say six lines, some say four; some say six words per line…). This is silly too, particularly in scientific presentations where long compound nouns abound. So what is the purpose of this rule? 1) to decrease the amount of text on a slide, so that the slide remains readable; 2) to prevent long lists that remove the need to try and select what is important and leave out what is less important; 3) to force the presenter to be concise as opposed to verbose; and 4) to allow the slide to be presented in less than 90 seconds; and thus maintain visual interest by not keeping the same slide on the screen too long – a point already covered above. What is important here is, again, the “Less-is-more” principle: the need to be selective to be  legible, AND to be intelligible (clear), and finally, the need to keep visual interest with something other than words.

There is however one rule of thumb I like… but then again, because it works for me does not mean it works for you. This rule of thumb is based on your arm length and your palm size. It determines whether the text on your slide will be readable once projected on the large screen in front of your audience. Readability of text is not to be decided on the grounds that you can read everything on your PowerPoint slide, while sitting one foot away from your computer screen. High screen resolution and brightness will even allow font size 7 to be readable! So if your arm is long enough and your hand is not super tiny, and most of all, if you do not look like a chimp, this rule of thumb might work for you.

Start your slideshow. Stretch out your arm and turn your hand horizontally, fingers pointing to your left if you are right handed, and vice versa. Move away from your computer screen until your stretched hand hides the screen. Remove your hand (but do keep it at the end of your forearm) away from the screen. If you can read everything on the screen from that distance, chances are your audience will be able to read it too, once that slide is projected. Oh, by the way, if you really want to be sure, turn down the brightness of your screen to 50% and move back one half meter more 🙂

By Jean-luc Lebrun


Effective Variant on the Assertion – Evidence Paradigm

The Assertion – Evidence paradigm, promoted by Michael Alley, does indeed force the presenter to limit the information on each slide (and less is mostly more, even in scientific presentations – see limitations). But does Assertion follow Evidence, or Evidence follow Assertion as in the traditional scientific order? To determine which order is more effective, I seeked the opinion of the scientists in the audience during my communication skills seminars. Some do not care about the order. But some prefer to see the evidence before an assertion is made – particularly if a question is raised prior to showing the enlightening visual evidence. When asked to probe this visual evidence for answers, their mind leaves the passive show-me mode to enter the active let-me-see mode. They are more involved and interested. When they discover the yet-to-appear assertion by themselves, under the friendly guidance of the presenter, they are more likely to be convinced by it and more likely to remember it when it is revealed.

Food for discussion.

Here is an example:





Text and visuals by Jean-luc Lebrun

Presentation traps 6 – the conclusion traps

Think about it. You have done your best to gather the interest of your audience around your topic for a full eleven minutes. The chairperson just looked at his watch, and corrected his sitting position to move closer to the microphone. Your talk officially ends in one minute. If you play the prolongations, it will be at the expense of your three minute Q&A time during which you intend to identify who else is interested in your research for later networking opportunities. You want to keep to time. So far, so good. You bring up your conclusion slide… and you are in danger of falling into one of three conclusion traps.

1. Your conclusion slide is a summary of your results.

2. You know you are close to the end of your talk, everything has been said, and you rush through that slide, simply reading its bullets.

3. You do a great job with your conclusion slide, and after clicking one last time the next slide button on your presentation remote, you land into one of the following slides: a) the black screen indicating the end of your presentation (a PowerPoint feature); b) the traditional Acknowledgment slide; or c) a black slide on which the words “Thank You” are written in Font size 88 – for good luck 🙂

Everything you have read so far does not explain why the image used in this post (Source Flickr, author Shenghun Lin) is that of someone running a relay race. You are about to discover why.

Conclusion trap 1 – the blind hand-over of the relay baton

The conclusion is the place in your talk where you will hand out the relay baton to those in the audience who could benefit from your scientific contribution. You want these people to read your paper, or to ask you questions, or to network with you at the end of your presentation. And you certainly want them to know how what you have discovered can be of value to them. Therefore, the conclusion slide is not about your results, your research outputs; It is about the audience “Take-Away”, your research outcomes. That is why I used the metaphor of a relay race. With your conclusion, you will hand out the part of your research that is directly applicable to the people in the audience. You might argue that “anyone is able to judge the impact of my work. I do not need to state it.” What you say is true for the experts in the room. The non-experts, however, are often unable , for lack of knowledge, to determine what these outcomes are, and how they are of value to them. You must see the hand of the next runner. You must have identified and thought about the people who were the most likely to benefit from your work. Do not hand over the baton with your eyes closed!

Conclusion trap 2 – the dropped relay baton

Singers know that the two places in a song that matter the most, and which they rehearse the most, are the beginning and the end. Often, because presenters do not control their time well, they rush through the conclusion slide  (and read it). Or, because presenters are exhausted by the time they reach the end of their talk and want to end it quickly, they do not even bother to comment on that slide and let the audience read while they just thank the audience for their attention. There is no call for action, no USE MY RESEARCH FOR THIS OR FOR THAT. As a result, the relay baton is not properly handed over, it is dropped on the ground before the audience has had a chance to grab it. They may still do, but the momentum gathered through your words will be lost. What a crying shame 🙁 This time with the audience is face to face. It is a time to plea, to sell, to tease, to encourage, not a time to turn your back on the audience and read in a flat low tone. Surely, having rehearsed your conclusion slide so many times, you know by heart what appears on the screen after each mouse click, and never need to turn to it.

Conclusion trap 3 – the fumbled hand-over of the relay baton

The last slide of a presentation is the conclusion slide. Don’t fumble this. It remains on the screen until one of the questions demands that you bring another slide to the screen. The reason why it is not a thank you slide is because having the computer say thank you on your behalf is demeaning. You are the host; the computer is only there for support. The reason why your conclusion slide should not be a black screen is because you must help the audience remember the main perceived advantages of your research by maintaining the conclusion slide on the screen, at least until you move to another slide in answer to a question. And finally, the reason why the last slide is not the acknowledgment slide is because acknowledgments are best given on the title slide (see trap 5 – the title trap); furthermore, time may have run out and you may have to skip that slide anyway – thus risking disappointing the sponsors attending your talk.

in conclusion – make your conclusion slide:  the last slide, the most audience-centered slide, the most rehearsed slide.

By Jean-luc Lebrun

continuity bugs in linear slide presentations

Whenever you take a non linear media and flatten it (make it linear), you introduce problems of two kinds:

1) Discontinuities in logic. The audience needs to remember what was connected to what, earlier in your presentation, to see the connection logic.

2) Discontinuity in time. As time passes, the audience remembers less and less of what they heard and saw. As a result, the memory fails to reconnect the time-broken strands of a disrupted argument.

Here is an illustration. Each square represents a slide. The slides are numbered from 1 to 5. The eroding effect of time on memory is here symbolized by the greying of colours, from dark (last slide best remembered) to grey (started to fade in memory) to dotted line (first slide, may have been presented 8 to 10 minutes before slide 5, vague or no longer remembered).

flattening problems

I assume here that all slides are equal in duration. Things worsen when slides are text heavy. We have all encountered slides that are so dense in information and take so long to explain that the audience has forgotten what was said at the beginning of the slide by the time the end of the slide is reached!

So here is my tip:

Visualize the logical connections between your slides, either as a domino or a graph. This will help you identify the potential memory-related problems your audience may face. And apply one of the following solutions to remove these problems.


The Announce technique consists in telling the audience what will be covered in the next (two) slides. The audience, once alerted, finds it much easier to keep the information of slide 1 in memory and relate it to slide 2 and 3.

The Repeat technique simply re-presents past information so as to be able to refresh fading memory (like the refresh cycle that keeps RAM memory alive!)

The Merge technique consists in keeping on the same slide all related elements, presenting them one by one (one at a time) to avoid overwhelming the audience with too much information at once, but allowing people to see past information on the same slide. Naturally, this is only possible if the slide can contain these related elements without losing readability.

The Restructure technique, as its name indicates, looks at alternative structures that would enable the contents to be presented without discontinuities.


By Jean-luc Lebrun

Learning from Henri Poincaré

Henri Poincarré

Henri Poincaré, the French physicist and mathematician was an outstanding scientist. In his book, La Science et la Méthode (Science and Method – Dover publication translated by Francis Maitland), he states that “to understand” means different things to different people. The scientists in your audience expect to be able to “understand” what is presented, so it is worth thinking about what people require to reach understanding. Poincaré identifies two classes of people: the validating and connecting type, and the associative and transformative type (my choice of words).

The validating and connecting type

“They want to know not only whether all the syllogisms of a demonstration are correct, but why they are linked together in one order rather than in another. As long as they appear to them engendered by caprice, and not by intelligence constantly conscious of the end to be attained they do not think they have understood.”

In other words, they need to see, understand, and find believable the fragmented evidence, but they also need to see, understand, and find believable the logical thread that connects these fragments together. Poincaré describes what happens when understanding is incomplete.

At first they still perceive the evidences that are placed before their eyes, but, as they are connected by too attenuated a thread with those that precede and those that follow, they pass without leaving a trace in their brains, and are immediately forgotten: illuminated for a moment, they relapse at once into an eternal night. As they advance further, they will no longer see this ephemeral light, because the theorems depend upon one another, and those they require have been forgotten.

You cannot memorize what you do not understand and further understanding stops as soon as memorizing stops.

Making sure that each slide in the presentation offers the right conclusions is not sufficient. The scientist who presents should also identify and explicitly reveal  and explain the logical connectors between any two consecutive slides.

The associative and transformative type

Others will always ask themselves what use is it. They will not have understood, unless they find around them, in practice or in nature, the object of such and such a mathematical notion. Under each word they wish to put a sensible image; the definition must call up an image, and at each stage of the demonstration they must see it being transformed and evolved. On this condition only will they understand and retain what they have understood.

Some may place more emphasis on evolution kinetics than on evolution logic.

These often deceive themselves: they do not listen to the reasoning, they look at the figures; they imagine that they have understood when they have only seen.

It is not sufficient to make sure that the content on each slide in the presentation is easily associated to prior knowledge and visually or conceptually connected to prior slides. The scientist who presents should also take the time to make explicit the reasons for the change in content from one slide to the next.

Since people understand things differently, the scientist who presents is well advised not to privilege one type of understanding (his own) over another. Therefore, to be effective, the presenter should do the following:

1) Since people need to validate what they see and hear at the level of a slide, give them the time to do so. Justify your logic, and ensure that each element on a slide is related to prior knowledge.

2) Because a slide delivers information in a discrete, and not continuous manner, each new slide introduces a discontinuity. Therefore, a bridge needs to be built between two consecutive slides. Verbally state the reason for the change in content that will be perceived by the audience.

By Jean-luc Lebrun

019 Dancing around outputs and outcomes

Did you ever wonder why your presentation, which looked and sounded awfully good, had little impact on your audience? The answer is found in this podcast… It is a matter of being able to tell the difference between a research output and a research outcome.

Learn more from our guest, Dr Leong Munkew, CTO of the SingaporeNational Library Board, a stellar presenter, and a brilliant technologist in the field of information retrieval.

(Photo by Zachstern, Flickr)

Blessed are the nitpickers

By Jean-luc Lebrun

If in every scientist lurks a nitpicker – a person who fusses over details – it is simply because scientific experiments require great attention to details. Nitpicking talents vary from one person to another. But, in any group of twelve people, I always have the good fortune to find one perfect representative of the nitpicking species. Nitpickers are part of any audience. They are easily distracted and annoyed by inconsistencies in your slides- and there always are inconsistencies such as misalignment, inconsistencies in font choice, size, colour, and style, inconsistencies in layout, spacing, spelling (spelling mistakes are very irritating), use of capital letters in titles, or inconsistent bullets. The nitpicker will even look at your clothes and nitpick on the way you dress, your choice of colours, etc… The nitpicker is by definition a neat and orderly person, with a particularly developed critical sense. Even if you are not, by any stretch of the imagination, a messy person, the nitpicker may find you “sloppy”, “careless”, or unskilled in design. If the nitpicker is your boss (or your spouse), you know what I mean.

Why are the nitpickers blessed? Because their talent is also a burden, to them and to others. Their highly developed critical eye is a curse. They have to repress their feelings because all that negativity in comments is not good for making friends. They need your gracious spirit. Given a chance to provide honest feedback, they will love you for letting them inspect your slides, particularly if you thank them profusely after their expert nitpicking feedback and take them out to dinner to show your appreciation. It does not matter how good you are, you will never beat the nitpicker at his/her game. And this is not a gender specific skill. Men and women are equally gifted.

The nitpickers are blessed because, without their honest feedback, your slides could be considered sloppy by some in your audience… including people who could influence your career. To them, sloppy slides points to the sloppy or junior researcher. Even if that deduction is far from the truth, you cannot afford to have people associate the two.

Therefore, when your presentation is prepared, and prior to delivering it in front of your audience, identify a nitpicker and ask for help in debugging your presentation to remove all pesky misalignments and inconsistencies. Your audience will be impressed by your care and attention to detail. But give credit where credit is due: always look to heaven to thank the blessed nitpicker 🙂

(Photo by VMOS, Flickr).

What can the scientist who presents learn from Herbert Simon (Part 1)

Nobel Laureate Herbert Simon, in a 1969 article entitled “Designing Organizations for an Information-Rich World”, points out the problems created by the wealth of information.

A rabbit-rich world is a lettuce-poor world. […] Now, when we speak of an information-rich world, we may expect, analogically, that the wealth of information means a dearth of something else – a scarcity of whatever it is that information consumes. What information consumes is rather obvious: it consumes the attention of its recipients. Hence a wealth of information creates a poverty of attention, and a need to allocate that attention efficiently among the overabundance of information sources that might consume it.

Let’s step back from this world view, down to the ballroom where the scientist presents. The problems are similar. During a presentation both presenter and slides are competing for the attention of the audience. Attention, Herbert Simon points out, is not easy to divide.

Human beings are essentially serial, 0ne-thing-at-a-time devices. If they attend to one thing, they cannot simultaneously, attend to another.

Expecting the audience to discover alone how to connect what is heard with what is seen on an information-rich slide, is expecting far too much! Discovering which area on the slide is alluded to by the speech, requires much attention. Because attention, like the time it requires, is scarce, little attention is left for the later (and much more important)  stage of knowledge extraction from the message content. By the time the audience is ready to process the information, the presenter will often have shifted to a new area of interest. And the twain do not meet!

Matching what the eyes see with what the ears hear is not simple. It is not just a matter of helping the eye focus on the area being described (although it helps). The audience has to be familiar with the vocabulary and symbols used, and has to have prior domain knowledge before being able to match oral information with visual information. For example, display multiple colorful shapes on a screen, say a blue dodecagon, a red circle, and a green cone,  and ask the audience: focus on the polygonal shape with an infinite number of sides, and whose shape reflects light in the 620-670 nanometer range. The audience is presumed to have sufficient prior knowledge to identify the shape. But how learned is the audience? How much of the vocabulary used by the presenter is understood by the audience? And what is wrong with “look at the red circle”.

What can we learn from the time-bound antagonistic relationship between attention and information-rich slides?

1) Help the audience visually identify the object requiring people’s attention using the simplest possible vocabulary before you talk about this object, in order to minimize the demands on what will always be a limited attention pool.

2) Decrease the amount of information on a slide (by layering, pruning, or condensing) to a level that allows the audience to have more time to pay attention to what you say because it has less to look at, in a given amount of time.

3) Confine your oral comments to what is visually singled out –  To be matched, oral and visual information require co-location of attention. Synchronize the two. Do not digress.

By Jean-luc Lebrun

Robert Geroch suggestions applied to the subtitle of your talk

You will find Dr Geroch’s “suggestions for giving talks”, online. The paper is stored on, the open access site managed by Cornell University. I have read this excellent paper many times and recommend you do likewise. My intent is not to ask you to change the title of your  talk. As soon as your conference abstract or paper has been accepted, this title is pretty much carved in stone. It will bring the audience to you – and, justifiably, the audience expects the title of your talk to be the same as that featured in the conference program. A dull demagnetized title or a title replete with repealing highly technical keywords cannot be repaired post publication. Expect experts or sleepers to your talk. If, on the other hand, your title has centripetal appeal, if it is a centre of interest to experts and non experts alike, you can enhance its understanding and appeal, right there and then, on the title slide, by adding a subtitle that really makes your focus clear. A good subtitle is easily understood by ALL.

Dr Geroch writes

“Thus, for an audience of relativists, “Linearized Fields in a Kerr Background Metric” sounds technical, “Perturbations of the Kerr Solution” sounds dull, and “Black Holes are Stable” sounds good.”

Questions are often frowned upon by editors when used as titles, but they are always acceptable as subtitles on a title slide. “Can a mesocellular siliceous foam firmly entrap a catalytic enzyme?”, “what if we could actually firmly entrap a catalytic enzyme in a mesocellular siliceous foam?”  Notice that the expectations set by these two questions are different. The first question focuses the audience on the couple of words “firmly entrap” – a method -, while the second question prepares the audience to a presentation of the outcomes of firm catalytic enzyme entrapment.

Use the subtitle to guide audience expectations, but do not let that be an excuse to skip the presentation of the keywords that brought the audience to your talk in the first place.

By Jean-luc Lebrun

When The Scientist Presents Book Launch in Singapore today

When the scientist presents - book cover

Amazon page for the book and publisher page

Praise for When The Scientist Presents:

Roald Hoffmann
Nobel laureate in Chemistry and writer

“This is by light-years the best guide to designing and presenting lectures. Lebrun writes in a lively, direct way, and every page is brimming with good sense and practical hints. It’s just plain fun to read When the Scientist Presents, even if your lecture is perfect!”

Alastair Curry
Royal University of Phnom Penh, Cambodia & Former Senior Lecturer, University of Hertfordshire, UK

“In this masterful and enlightening contribution, Lebrun builds on his reader and writer’s guide to ‘Scientific Writing’ to expose the essential ingredients of effective scientific presentations. Fresh and entertaining, full of practical advice and highly readable, this is a most instructive and enjoyable work. Postgraduate students, supervisors and many an experienced researcher will welcome and benefit tremendously from this book, together with its wealth of accompanying resources, as an essential guide to effective communication.”

Lisa B. Marshall

Communication Expert & Blogger at “”

“Finally! A comprehensive, engaging book full of practical tips to improve the organization, the delivery, and visuals of scientific presentations. If you are serious about your professional success, then I strongly recommend you read this book.”