How Much Text on Presentation Slides?

Posted on December 21st, 2012

I've been working on my presentations lately. While I've spent most of my time thinking about the content and the style of the talk itself, I've also been changing my thinking about the content of the presentation slides. Garr Reynolds, in his excellent book Presentation Zen, makes the following observation:

Over the years, a primary reason so many presentations given with the aid of slides or other multimedia have failed is that the visual displays served as nothing more than containers for reams of text. According to John Sweller, who developed the cognitive load theory in the 1980s, it is more difficult to process information if it is coming at us both verbally and in written form at the same time. Since people cannot read and listen well at the same time, displays filled with lots of text must be avoided. On the other hand, multimedia that displays visual information, including visualizations of quantitative information, can be processed while listening to someone speak about the visual content.

Most of us know intuitively that when given 20 minutes to present, using screens full of text does not work. Research supports the concept that it is indeed more difficult for audiences to process information when it is presented in spoken and written form at the same time. So perhaps it would be better to just remain silent and let people read the slides. But this raises the issue: Why are you there? A good oral presentation is different from a well-written document, and attempts to merge them result in poor presentations and poor documents.

Before thinking (i.e. reading what people smarter than me think) more carefully about what belongs on slides, I thought that slides including little text (e.g. one word or number taking up most of the page) were for non-academic presentations. I reasoned that as an "intellectual" presenting at an academic conference, I should provide a "serious" presentation that is not designed to entertain. I have since realized that a great presentations is not about entertaining, but about communicating (although entertainment will be a side effect). Great communication requires slides that do not contain much text. Great communication requires the presenter to speak to the audience about the idea, not read to the audience from the slides.

To give some sense of how my thinking has morphed on the topic, I provide some examples of slides I've used to convey the same ideas.

First, a Beamer slide from a talk I gave at Florida State earlier in the year.

A Presentation Slide with Lots of Text

In my experience, this is standard for the amount of text on a Beamer slide. It even seems that Beamer encourages this style of slide since the font sizes are more difficult to adjust. It just looks funny to have a Beamer slide without a lot of text. But since this talk, I've begun to realize that more text hinders good communication. So, I made a few changes.

I recently gave the same talk at the University at Buffalo and, rather than use Beamer, I built the slides in Impress, an open-source alternative to PowerPoint. Using the additional (or more accessible) flexibility offered by Impress, I used the following slide to convey the same idea.

A Presentation Slide with Less Text

Notice the change. I'm relying less on text and more on graphics and verbal explanations. But I'm still not quite there.

While make the same point at SPSA in January, I plan on simply using the following two slides. I'll use the first slide to explain the idea on the left slide of the slides above.

A Presentation Slide with No Text

I'll use a separate slide to explain the ideas on the right side of the "text heavy" slides above.

Another Presentation Slide with No Text

I haven't had the chance to test out the completely graphical approach in front of a live audience, but I expect it to go even better than the previous two talks. Indeed, I've realized that the more a speaker relies on speaking, the better the presentation tends to go. Indeed, the only alternative to speaking to the audience is having them read your slides or reading your slides to them. Neither communicates as effectively as relying on your slides to illustrate and supplement your words rather than replace them.