Show Me! What Brain Research Says About Visuals in PowerPoint

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By Robert Lane and Dr. Stephen Kosslyn

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We’ve all seen this view before—a blank PowerPoint slide waiting for content. Looking at the slide pane, is it any wonder that most new presenters think, “Oh, to make a presentation, all I have to do is type text”? And they do so—often with a vengeance. Slide titles and bullet points soon rain down upon audiences with hurricane force. Weary viewers face the equivalent of digitized books projected onto walls… or worse, they suffer the terror of presenters reading books projected onto walls.

Blank PowerPoint Slide
Figure A: A blank PowerPoint presentation

Yes, almost all of us go through this ‘typing phase’ when we first encounter the software, until we realize, “Umm … this just isn’t working. People are bored; they aren't understanding me as well as I would like.” Then begins a quest to figure out what should be shown. What will help individuals better understand, learn, and remember messages?” The answers to those questions are surprisingly complicated, and little research exists in a direct PowerPoint context to guide us. A quick look at brain functioning, however, at least gives some clues.

What the Brain Sees

It’s tempting to believe that, just like capturing footage with a video camera, our neural networks passively record all light entering the eyes. Such is not the case. For us to ‘see’ something, light stimulating our retinas must be converted to signals that are then sent to the cerebral cortex (the thin outer covering of the brain), where the signals are processed and mapped out in shadowy representations of the original input. That processing action throws away most of the original data, kind of like what happens when we compress digital movies or songs, to save space on our computer’s hard drive. Why does the world seem as complete as it does, if we in fact don't process the input very thoroughly? In part because we process the parts we are paying attention to pretty well, and in part because what we know supplements what we see.

What does all this mean to a presenter? Two issues in particular are important: processing efficiency and expressive potential.

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Processing Efficiency: As one might expect, not all visual stimuli are created equal. Some cruise through our neural circuitries with ease and others require more analysis. Text is a prime example of the latter. Asking people to read text on slides requires a lot of processing effort. Text, after all, is a symbol system and must be decoded to have meaning. That is, the brain first must compare letters and word-forms with shapes stored in memory. Then it gauges how the words fit together in the context of sentences, and so forth. All considered, reading is a lot of mental work. Granted, such effort may be perfectly justifiable while reading a novel and sipping iced tea in the back yard, but it’s not appropriate when trying to pay attention to a speaker who is talking at the same time.

Appropriate images, on the other hand, require relatively little processing because they fit with the message. Viewers routinely and efficiently observe visuals, analyze their meanings, and give attention to the speaker’s words, without a problem. That’s why watching television or movies is effortless. Showing people meaningful, content-based visuals, as opposed to text, lessens their cognitive exertion and improves overall experience. For numerous other examples of how visual design affects our brain’s processing capabilities, see Chabris and Kosslyn (2005).

Expressive Potential: Additionally, images often allow us to explain, simplify, or expand concepts in ways that are very difficult to do (if even possible) with text—or even with spoken words. The result of picture-based visual communication is improved learning and recall. Levie and Lentz (1982) looked at 46 experiments comparing pictures included with text, or text used alone, and found that 45 of the studies—all but one—showed that including pictures improved memory or comprehension. In one case, a group following directions in text illustrated with diagrams did an amazing 323% better than a group following the same directions without the illustrations. Obviously these studies took place long before the current PowerPoint era and investigated picture/text combinations mostly in the context of print media (books). One might reasonably presume, however, that similar effects apply to PowerPoint displays as well.

How Should Visuals Be Used?

Be careful, though, because not all picture-based visual stimuli are created equal. Simply throwing random pictures onto slides to “pretty them up” is not a good idea. Some researchers contend that including off-topic or irrelevant pictures and video clips in educational materials actually can have negative effects on learning. See Tversky and Morrison (2001), Mayer, Heiser, and Lonn (2001) and Mayer (2003).

Stock Photos Provide Little Value to Audiences
Figure B: Examples of stock photos

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The cognitive system is a fantastic relevance detector. It constantly tells the perceptual system, “Hey, spare me the fluff and give me only the facts I can use.” At the same time, pictures attract our attention like magnets. Can you see the dilemma? If irrelevant stock photos (such as those shown here) appear frequently on slides, purely for decorative reasons, the eyes will respond automatically and then the brain has to make sense of them. Subconsciously, the viewers will be thinking “Why am I being distracted by that visual input? These pictures don’t relate at all to what the guy is saying.”

On the other hand, pictures can be powerful conveyors of meaning. Here are a few good practices:

  • Provide Detail: If showcasing a product, for example, have short video clips available that demonstrate its operations, along with pictures displaying various views, zooms, and environments. Obviously such imagery is especially helpful if the product is not available at the speaking location. Show and tell.
  • Shape Emotions: You've been asked to give a talk about the dangers of tobacco use. A bullet list might do the job, but imagine the greater emotional impact provided by showing yellowed teeth, blackened lungs, and mouth cancers. Emotions can be powerful motivators and pictures tap directly into our emotions, at the deepest levels.
  • Lay Down Context: You can provide a priceless benefit to audience members by grabbing a digital camera and documenting the environment and context surrounding your subject matter. Try to capture what you see through your eyes or imagine in your mind and bring that world to your audiences. They will relate to your topics and perspectives with greater ease.
  • Simplify or Clarify Complexity: Those of you who present technical information are well aware of how confusing your specialty may be to people in related fields, or sometimes even to experts in your own field. Showing pictures, video, and animations to make topics more concrete will help viewers connect the concepts you express verbally with experiences they’ve already stored in memory.
  • Give Examples: The phrase, “Here, let me show you what I mean”, is one of the most potent set of words you can utter as a speaker. It rivets attention in expectation of visual relevance, something the brain appreciates very much. Whether it's warranted or not in this age of photoshopped illustrations, for most of us, seeing is believing.
  • Reduce Learning Times: Are you a teacher? Most of us are in one way or another, or we wouldn’t be in front of an audience in the first place. Showing a well-timed visual, or sequence of visuals, can deliver instant understanding in some situations, and therefore substantially reduce explanation time.
  • Enhance Verbal Stories: You may be thinking, “OK, but why should I be so concerned about using imagery if I’m a good storyteller? Storytellers ‘paint images in people’s minds’, right?” Yes and no. With words alone you can paint something in those minds, but exactly what will remain a mystery. Your listeners can attempt to see the image you are painting, but in doing so they must call upon the shadowy mental imagery currently stored in their heads, based upon past experiences. Their understanding, ultimately, may or may not look anything like what you see in your mind. It is a much safer bet to literally show them what you mean, in conjunction with telling a verbal story.
  • Improve Memory Recall: A picture can enhance the ability to remember concepts and details, and such an effect tends to increase over time. One study showed that illustrated text was 9 percent more effective than text alone when comprehension was tested right away, but that it was 83 percent more effective when the test was delayed, thus implying the reader’s ability to remember the information better later, because of the illustration (Rusted and Coltheart, 1979).

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A Visual Example

Here’s a simple example of how visuals can speed learning and express meaning in ways that might be difficult or impossible to convey otherwise. Pretend that you will be visiting the UK and someone mentions the London Eye. In all likelihood, some of you reading this article know exactly what that phase means. Some have heard of it or even seen it. Some of you, however, don’t have a clue what a London Eye is. It could be a famous painting, a mysterious religion, or a popular brew in a local pub for all you know.

If I say you can ride it … that gives more information. If I say it looks like a Ferris wheel, perhaps that helps—or not. What if you live in a part of the world that doesn’t have Ferris wheels and you’ve never heard of one? I could say that it’s round, that it plays with physical forces like a bicycle wheel, that it has capsules. I could spend the next half hour trying to verbally ‘paint a picture’ inside your brain, but that painting, that visual story, probably will be incomplete—until I show you this thing.

Using a Picture as Real Content in a PowerPoint Presentation
Figure C: A side view of the "London Eye"
Using a Picture as Real Content in a PowerPoint Presentation
Figure D: A close up of the "capsules" on the London Eye
Using a Picture as Real Content in a PowerPoint Presentation
Figure E: A view from inside a capsule on the London Eye

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In a fraction of a second, you dissect, code, and analyze the visual signals for meaning. “Hmm…it does kind of resemble a bicycle wheel, and those must be the capsules, and that’s what he meant by riding it.” In a presentation context, of course, such visuals should be shown along with verbal descriptions and/or simple textual labels. Related visuals like these, when used in succession during a performance, are called a picture story (Lane, 2007).

Keep in mind, also, that this kind of mental meaning search is not unique to pictures. Similar methods guide the analysis of patterns and representations of data, such as graphs, tables, and diagrams (Kosslyn, 2006).

We also recommend another good practice: displaying content-bearing (not decorative) pictures full screen (allowing them to cover the entire slide pane), perhaps without adding text at all. Then fill in contextual details verbally. Most presenters who use pictures do otherwise. They place a small image off to the side of text, as in the screenshot shown below. Ask yourself, though, “Is that text really necessary? Can those facts be offered verbally instead?”

Make a Picture Large and Exclude Bullet Points if Possible
Figure F: Some facts about the London Eye on a slide

Here’s the issue: As noted previously, text and pictures are two very different forms of visual information, yet they compete for perceptual and cognitive resources when juxtaposed. You can focus on one or the other, but not both at the same time. Going back and forth between text and picture would be OK if reading a book at leisure, but in a speaking environment, time is more compressed. Viewers must try to read the text, look at the picture, and pay attention to the speaker’s words all in a short timespan. Most of us fail to do all three.We either ignore the text and listen to the speaker, or try to read the text and miss the speaker’s words. Having the written text on the slide interferes with other forms of information gathering. See Kalyuga, Chandler, and Sweller, 2004, for an experiment in a corporate training context.

To avoid having the text conflict with the picture, or the text conflict with the speaker’s verbal stream, the solution is obvious: simply dump the text and use a full screen visual. But make sure that your visual is the ”picture that tells the story”.

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