Summer SciComm Series: Cognitive Load

By Rachel Leeson

We are now at the second post in our Summer SciComm series and it’s time for one of my favorite scicomm bandstands: cognitive load. 

Cognitive load

The Wikipedia definition of cognitive load states: “cognitive load refers to the used amount of working memory resources. There are three types of cognitive load: intrinsic cognitive load is the effort associated with a specific topic; extraneous cognitive load refers to the way information or tasks are presented to a learner; and germane cognitive load refers to the work put into creating a permanent store of knowledge (a schema).” 

In scicomm, I like to think of cognitive load as the amount of mental thought and effort your audience needs to understand what you’re communicating. While I’m sure that there are loads of ways psychologists define and explain this concept, the best way I’ve come up is this: It takes me about the same amount of time to read a 100-page genre fiction novella as it does to read an 11-page Cell paper - and sometimes, it might actually take me less time to read the book. 

Intuitively, this probably makes sense. It’s a lot easier to read a formulaic fiction story that doesn’t require any detailed retention of information or formulation of new knowledge than it is to read a manuscript whose whole purpose is to provide detailed evidence of knowledge new to mankind. And you probably understand how much faster it would be for an expert in the field to read this paper than it would be for an undergrad taking their first upper-level class. Even so, it’s quite easy (and common!) to be blind to the cognitive load you’re placing on your audience when you're in the midst of sharing your science - which can drive away even the most enthusiastic of learners. 

What contributes to cognitive load? 

Everything! Here are some common areas that can use up your audience’s mental bandwidth. 


Learning, using, and retaining new vocabulary takes time and effort (otherwise it would be a lot quicker to pick up new languages!) Jargon has a place in science communication, but the more you use, the higher cognitive load you are asking your audience to take on, just to understand you at the most basic of levels. 


This can be obvious, in that a lot of science communication is helping people understand new concepts. You hopefully are aware that this takes a good deal of mental effort, and that some concepts are easier to grasp than others. But sometimes we’re unaware that we are leaning on an unspoken expectation of our audience knowing foundational concepts (that they often don't!) to understand us, or being able to connect one concept to another which leads us to…


Learning to think like an immunologist, a geneticist, a physicist, etc., is an immense task (it takes, ooh, approximately the length of your average PhD to achieve!) Each field has its own framework: a particular way of organizing and connecting information and a logic to the types and timing of questions that are asked. Many things, therefore, will be obvious, intuitive, or logical to a biologist that are not at all obvious, intuitive, or logical to a layperson. When you’re communicating ideas that you think are clearly connected, step back and ask yourself, “are these clearly connected because of the specialized knowledge and context I have spent years striving to obtain?” If the answer is yes, you will need to spell out that connection for your audience. I ask myself that question constantly (and so should you!) 

Amount of information and level of detail

Again, this is an obvious one on the surface, but it’s quite easy to add in “necessary” detail after “necessary” detail and end up completely overwhelming your audience - like the professor who once decided that to teach high school students PCR, they first had to understand hydrogen bonds and then build up from there. In every project, time, attention, and/or length restraints mean you will have to pick and choose what concepts and details to communicate. It’s okay (and encouraged) to leave blank spaces or to gloss over some aspects when needed. The trick is to communicate your key points well enough that the audience can take that knowledge and continue building on it as they learn more from other sources.

Mode of communication

Different modes of communication take up different amounts of mental bandwidth - if not exactly cognitive load, than certainly amount of attention and information input. If you’re reading a book, you only have the words to focus on. If you’re reading an article online, you have the words and maybe a few links or ads that are vying for your attention. If you’re reading an article with images, now you have words, images, and links to pay attention to. If you’re watching a video, you now have moving images, noises and music, spoken words, and any onscreen text. Be aware of the effort the audience is expending to pay attention to the mode(s) of communication you choose. 

Audience knowledge

We already touched on this briefly, but the amount of knowledge and expertise your audience has is a major factor in how quickly they can understand and process your information. A class of three year olds is unlikely to be able to follow a YouTube video on PCR, while a senior lab scientist is likely to be quickly bored by it. Oftentimes, it can be quite difficult to ascertain what your audience knows, but the following tips can help: 
  1. If there’s a teacher, mentor, or other educator working with your audience, ask! They are experts in what their students know.  
  2. Ask the learners themselves for feedback in a variety of ways, like having them restate or summarize the concepts you’re covering. Don't show frustration if they're incorrect; take it instead as valuable feedback. 
  3. Listen. Think about the questions you’ve received, read the comments, seek feedback from others, and listen quietly as people discuss their experiences. If you’re hearing multiple people with similar misconceptions, it’s time to rework your strategy. Don’t assume it’s the audience’s fault; instead look for ways to improve how you're communicating your science

How much is too much? 

So now that you have all this knowledge, the question is: How do you know what’s too much (or too little)? 

The answer is: it depends! The important point here is to pay attention to exactly what you're asking of your audience and when things aren't working out, adjust the ask. 

I used to do a lot of outreach to student groups and being aware of cognitive load changed the way I thought about engaging with learners. If something I was communicating didn’t click, instead of blaming the audience, I would think about how I was presenting the information. Maybe I needed to remove a distraction, such as pausing or turning off the slide deck (or reminding them to put their phones away), or maybe I was assuming something was intuitive that actually wasn't. Maybe I needed to employ a visual aid instead of describing something verbally. Sometimes a group was just really tired and needed a slower, simpler presentation than I had planned; other times students were fired up and enthusiastic and needed a faster presentation with more information than normal. I had to learn to observe and adjust on the fly. 

Once you can think about everything you’re asking your learners to do, it becomes a lot easier to build successful, accessible pieces of communications that drive engagement with your target audience. Thinking about cognitive load will help you understand why you’re not communicating as clearly as you intended (it happens to us all!) and offer a variety of options to make your content more accessible to your audience. 

More resources on the Addgene blog

Intro to our Summer SciComm Series

Topics: Science Communication

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