If you read our blogs, you’ll notice that we talk a lot about making whatever you publish about science easy to understand. This may feel repetitive sometimes. And being scientists ourselves we get why you may think it’s the least important part of any presentation. But science communication is here to stay, so it pays to learn to do it right. To quench that thirst for a more in-depth explanation, here’s an entire blog devoted to why we think it is key to any talk, article or website to be easy to understand.

Introducing mental bandwidth

Every person, no matter their education, background, gender or income, has a certain capacity for retaining, processing and remembering information. This is described by the Cognitive Load Theory, which states that people have a limited short term memory and working memory. To make it easier to talk about, we pooled these limited capacities into ‘mental bandwidth’. It’s a nice metaphor because cognitive load does resemble your internet connection: when you’re just emailing and browsing everything is fine, but download and install a large game or software update, and you reach the limits of your connection and every activity just goes a little bit slower.

Listening and reading at the same time doesn’t work

Your bandwidth is most obvious when you’re dealing with two competing streams of information, say listening and reading at the same time. This is why bad slides full of text or unclear information are so detrimental to the success of a presentation. You are confronted with a slide with the fluffiest graphs, vague text (and lots of it!) and no conclusions, you will stop listening and devote all your mental bandwidth to the ‘puzzle’ on screen. Not until you solve it and arrive at the conclusion of the graph and slide will you direct your attention back to the speaker. You have missed everything he or she said for a while – and it’s another assumption that you’ve arrived at the right conclusion.

Jargon will do the same thing: you have to mentally look up a definition, and the more unfamiliar the term or the more often you have to do this, the longer this will take and the less likely that you will keep reading or listening. And you can even do this to yourself! Who hasn’t been in the situation where you put on a show on Netflix and then after a few minutes think ‘I’m just gonna catch up on the news or that one paper’? In the end, you’re not really paying attention to the paper or the show…

Mental bandwidth changes per person, per situation

Cognitive capacity – bandwidth – varies between people, but what doesn’t change is that it’s finite. It’s taken up by a variety of things. When you have to keep track of a shopping list you are using bandwidth, or when you have to remember until what time your parking meter has been paid. But it also works on a longer term: financial troubles or a sick child can take up a lot of bandwidth for months or years. And it doesn’t have to be negative: buying a house or being in love or pregnant is very exciting, but they do tend to distract you as well.

Not all burdens are created equal

Some people are incredible at keeping lists in their head, while others are great at dealing with insecure teenagers. In other words, the burden that a certain task or event poses is also different for everybody. There’s no standardized unit for ‘bandwidth claim.’


This makes it very hard to predict how much bandwidth you can actually claim when you approach people with a story. Whether it’s a presentation, a website or a worried patient sitting at your desk, you have no way of knowing what the capacity is that you can claim from that audience. Therefore, you have to turn it around: to be sure that the message comes across, you should assume that that capacity is very small and minimize your claim.

How to minimize your claim of bandwidth

Having a clear story helps to savor bandwidth, because you create a framework for the listener that allows bits of information to fall snugly into place. This takes up much less effort than when your audience has to think about every bit of info in their head and try to make sense of it. When your story isn’t clear you might lose them, and because they are more unlikely to latch back on later when the topic is complicated, you could have lost them for the remainder of your conversation, talk or article.


Even if your audience is gifted or in the same field, you never know what else is going on in their lives. It’s simple: don’t claim more than you need!

Don’t turn your presentation into an IQ-test


Hopefully this helped you to realize a little why we hammer down on that comprehensibility message so hard. And yes, it’s hard work to make science communication easy! But from an economic perspective; it’s better that you put in that effort by yourself, than that you’re going to request that effort from all of your audience.

If you’re ready to learn more, attend our workshop Basics of Science Communication, and if you have any questions or thoughts about this, let us know!

About the Author: Stephan van Duin

Stephan enjoys the process of understanding complex matters and being able to present them in a comprehensible way. His vision is that science and society can benefit from clear science communication, and that technology can aid this development in various ways, from science websites for the public to academic e-learning for students.

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