People can’t read and do much else at the same time. This is why people who try and text and drive have significantly worse response times than intoxicated drivers, and why phones pose one of the single largest dangers to pedestrians in the last fifty years:


Keep this in mind as you’re developing your presentations. Your audience simply can’t read and listen at the same time, so we have to limit the amount of text or complex graphics we introduce simultaneously.

We Can Learn a Lot from Cognitive Science

For decades, cognitive scientists have explored how the human brain processes text and other sensory input. As presenters, our ultimate goal is that our audience leaves remembering our presentation. Fortunately for us, numerous studies focus precisely on how people learn when simultaneously presented with multiple formats or modes of media. These studies explore the impact of, for instance, an individual attempting to read (visual mode) and listen (verbal mode) simultaneously.

This is precisely what happens in many presentations when presenters read large sections of text to their audience while the audience is simultaneously reading the text from the presenter’s slide.

Richard E. Mayer, PhD, an educational psychologist at the University of California, Santa Barbara, is one of the world’s leading experts on how people learn. Mayer has produced a wealth of research on how people process different modes of information (like visual and verbal) simultaneously. In a 2004 interview with Cliff Atkinson, Mayer directly addressed slide design, saying:

“In order to create effective PowerPoint presentations, it is important to understand how people learn. In particular, cognitive scientists have discovered three important features of the human information processing system that are particularly relevant for PowerPoint users:

dual-channels, that is, people have separate information processing channels for visual material and verbal material;

limited capacity, that is, people can pay attention to only a few pieces of information in each channel at a time; and

active processing, that is, people understand the presented material when they pay attention to the relevant material, organize it into a coherent mental structure, and integrate it with their prior knowledge.

The implications are that: 1) PowerPoint presentations should use both visual and verbal forms of presentation, 2) filling [your] slides with information will easily overload people’s cognitive systems, and 3) the presentations should help learners to select, organize, and integrate presented information.”

(formatting added) Additional resources: Mayer’s cognitive load theory and potential ways to reduce the liklihood of cognitive overload.

Lighten the Cognitive Load

One pervasive piece of misinformation that I frequently hear is that by presenting text on the screen, a presenter is engaging “visual learners” and that by reading it out loud, they are engaging “auditory learners.” The idea that there are different types of learners or learning styles has been thoroughly refuted in numerous studies.

While your audience is made of unique individuals, you do not need to present and read text aloud to target different types of learners in your audience. Instead, you should focus on presenting your material so that it requires the least amount of mental work, or “cognitive load,” for your audience. Mayer’s findings champion a combination of verbal presentation paired with images or video. The less mental work you subject your audience to, the more likely they are to stay engaged with you and retain information from your presentation.

Check out Part 2 of this post for more details of the cognitive mechanics happening during your presentation as well as an example of how you might convert a text-heavy slide to something that your audience can process easily.

Cover photo from Pexels.