• Akos Gerold

Avoid the biggest mistake in delivering slide presentations — Understand Presentation Mathematics

Updated: Jan 28, 2019

Presentation Mathematics is simple. But not understanding it is costly.

How much is 1 + 1 in a presentation?


Yes, 1 + 1 = 0.

And that is roughly how much your audience will remember from what you say if you don’t understand this equation. I call it Presentation Mathematics.

How does Presentation Mathematics work?

If the presenter talks (the first 1 in the equation) at the same as when they show visual information in a slide which takes longer than up to three seconds to absorb (the second 1), the audience will remember nothing or almost nothing (= 0).


Because despite what we would like to believe about ourselves, we are unable to pay attention to two simultaneous activities that require mental focus. And following what someone says and understanding visual information (written text, a graph, a pie or bar chart, etc.) are two such activities.

So how can we avoid this mistake?

By not putting our audience in a situation where they have to do the two things SIMULTANEOUSLY.

If we don’t make them listen to us at the same time as we give them visual input that takes longer than up to three seconds to absorb, then they will avoid the deathtrap which so many presenters set for their audiences and their presentations without being aware of it.

How to put this into practice?

Just follow a few simple guidelines that make slides and the delivery of a slide presentation brain-friendly.

1) Reduce the amount of text in a slide to the absolute minimum (only the key word or phrase) and to a supporting picture if you will keep taking while showing the slide.

The full sentence in the below slide is a lot more than we need to have in a brain-friendly one. (And just remember how often you see much more text than this in slides.)

Instead, reduce the text to the bare minimum by focusing on the essence of it. And say the rest.

2) Show the slide with the key word or phrase at the same time as when you say them. Not before. (Use presenter mode on your computer to know which slide is coming next so you can synch what you say with what you show.)

Presenter view -- Your computer can show the current and the next slide both in PowerPoint and Keynote.

3) Avoid bullet points in slides, even if the text in them is reduced, as they typically provide more visual detail than can be mentally digested in up to three seconds. Many presentations have died or were heavily wounded by the bullet points in them.

So instead of:


(each as a separate slide)

4) If for whatever inconceivable reason you still insist on bullet points, grey out the ones you are currently not talking about, while keeping the text in each to the mentioned absolute minimum. This will prevent the audience from reading ahead. Nobody can help themselves do it. So if you give it to them, you are setting them up for getting to the zero in Presentation Mathematics.

Instead of:

Use the following multiple slides:

Notice how the bullet points that you are not talking about are always greyed out so that they are barely visible. Your audience will know they are there, but they won't serve as distractors.

5) If you need to show graphs, tables or diagrams, tell your audience what you are going to show them before you do so. Then show it to them for about 30-40 seconds while not saying a word.

(Or an example for a graph.)

This way, they will have the overview of the bigger picture and all the details, which some kind of audiences like.

Finally walk them though the important details in the graph, table or diagram while greying out all parts of it that you are currently not talking about. The greying out will ensure that they don’t try to read or make sense of the parts you are not addressing at that moment and thus they will not be distracted from what you are saying.

(An example of walking your audience step-by-step through the relevant details of a table instead of talking about details in the table while showing it in full. Each slide is used in a separate step and you should talk only about that step while the rest of the table is greyed out.)

(The same approach applies to graphs.)

If you apply the above, you will be able to direct your audiences attention to what they need to focus on, just like a film director does, so that nothing distracts them from your storytelling.

The result?

You will sell your products, services and ideas better.

What I have described here is part of what makes slides brain-friendly. I will be exploring the above and much more in greater detail in my Brain-Friendly Slides workshop at the Munich Creative Business Week on 9th March.

Happy presenting!

#mcbw #cokreamcbw19 #brainfriendlyslides #munich #presentation #slides #publicspeaking #visualstorytelling #presenting #presentationslides

get in touch to see how I can help you

Akos Gerold

Brasília, Brazil


Tel: +55 61 99880-9919

WhatsApp: +55 61 99880-9919

akos (at)

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