When I ask faculty or students to list their most ineffective learning experiences in college or professional life, some aspect of the use of PowerPoint is always on the list. “Death by PowerPoint”, they commonly say. In fact, if you search for “death by PowerPoint” in GoogleTM, you will find more than 3.5 million hits. So, it’s not surprising that it seems like everyone has an opinion on how to make a better PowerPoint presentation; search for “PowerPoint tips” and you’ll find more than 26.7 million links. What is astounding, however, is how much of this web-shared wisdom recycles myths and ignores the research on design of visual aids for learning during an oral presentation or even the legibility of the slides. What does the evidence actually say for the maximum number of bullets to include on a slide? Zero. Isn’t it true that we should use blue background because blue is calming and increases a sense of pleasantness? Try again.
When criticizing “PowerPoint-enhanced” presentations it is important to separate the fault of the presenter from the fault of the program. The program can actually accomplish a great deal to support effective learning during a presentation, primarily by supporting visual learning. The problem rests with how it is used, especially when the presenter applies default templates that encourage meaningless titles, bullet lists of text, and distracting color-graphic backgrounds that have nothing to do with the presentation content. Bullet lists are arguably most useful for the presenter, giving him or her something to read or to prompt memory. The development of bullets in the software was a response to the original buyers of the product – the business world. Catchy marketing phrases and lists of a few take-home productivity points were key aspects of the 1980s business meeting. Slide templates that met the needs of this original PowerPoint market were then utilized, due to ease of access, by all PowerPoint consumers. Henceforth, bullet lists became the socialized norm for visual presentation in everything from elementary-school book reports, to battlefield preparation, to the uninformative technical briefing that is partly implicated in the Space Shuttle Columbia disaster. There is no indication that such brief outlines actually facilitate learning so why should educators use these templates? Even one of the inventors of PowerPoint, Robert Gaskins, is baffled: “The real mystery to me is why PowerPoint, including its default presentation style based on traditional business presentations, has been adopted so widely in other contexts.”
So, what does the research on learning from combined visual and oral presentation offer for more effective use of PowerPoint? A great place to start is the research by Richard Mayer on reducing cognitive load in multi-media presentations. We can think of cognitive load as the effort expended by working memory when a learner tries to comprehend new information. The learner in the PowerPoint classroom takes in auditory sensory inputs from the speaker, visual inputs from the slide, and tries connecting them to previously encoded relevant facts and concepts that are simultaneously retrieved from long-term memory. Working memory endeavors to successfully manipulate all these inputs and prior knowledge in order to encode a new, retrievable memory – that is what learning is all about.
Mayer’s research clearly informs us to say it, don’t write it – leave the bullets off the slide. Part of this reasoning comes from Mayer’s principle of modality, which emphasizes that deleterious cognitive load is increased by simultaneously presenting information in printed and auditory modalities. The verbal and auditory inputs from the speaker and slides, respectively, are processed in different parts of the cerebral cortex and are maintained as separate channels into working memory in the frontal lobe where they are combined for understanding. Delivering the same information in both channels is not helpful. The problem largely arises from the phonemic nature of the letter-based (as opposed to character-based) languages. Letters and combinations of letters represent sounds and the meaning of words and their context in sentences requires the auditory cortex to be involved in the understanding of written words. You probably already know this from experiencing the sensation of “hearing a voice” inside your head as you read (Note to self: hearing these voices is not indicative of psychosis!). So, the auditory channel is being overloaded if the speaker is saying what is also present as slide text.
So, if you’re leaving off the text (or at least most of it), what should be on the slide? Mayer’s principle of modality, along with the principle of redundancy, specify the best approach: Provide images that are complementary to your narration. The visual processing system in the brain evolved to make sense of shapes, colors, and spatial relationships. Written language has existed for only about 5000 years and the neural plasticity required to make sense of the visual processing of text is, frankly, unnatural. Therefore, instead of asking the visual channel to compete with verbal information that can be completely offloaded to the auditory channel, use the visual channel for what it naturally does best: Make sense of images. Images also accomplish things that text, alone, never can. Images (sometimes with sounds) can provide concrete representations of what is being said and trigger visual memories. Images can include graphic organizers, such as flow charts, concept maps, or mind maps that help the learner see the connections between multiple new concepts. The last sentence also points to what Mayer’s research describes as the signaling principle, which emphasizes the benefit of presenting structure and relationships of the concepts that the learner needs to process in working memory.
Signaling is not only accomplished by graphic organizers but can also be verbally cued by the speaker and through an appropriate slide headline. Yes, that’s right; a headline, not a title as shown in the PowerPoint template. Headlines in print and online news media are assertions that tell you factual information, even if you read no further. If you want to know the basis for that assertion, you look for the evidence to support it in the remaining text. Assertion followed by evidence is a standard rhetorical approach. So, the text at the top of your slide shouldn’t be a centered, huge-font title. Instead, it should be a left-justified, sentence-structure assertion that simply and explicitly states what it is that you want the learners in the audience to know from this slide as you present it.
Putting all of these concepts together leads to a new template for your PowerPoint slides: The Assertion-Evidence template. The headline asserts what the learner is supposed to learn from the slide (and accompanying auditory explanation) and the remainder of the slide presents the visual evidence to support that assertion with minimal use of additional text. If you want to see many examples of this approach then you will want to visit the resources provided by Michael Alley, Associate Professor of Engineering Communications at Pennsylvania State University.
Alley and his colleagues have demonstrated greater learning comprehension, particularly of complex topics, when using the assertion-evidence template rather than the traditional PowerPoint defaults. For another example, I turn to the work of Nabil Issa and his surgery colleagues at the Northwestern University Feinberg School of Medicine in collaboration with Mayer. As shown in the illustration below, depicted as contrasting PowerPoint slides, students learned more about the treatment of hypovolemic shock when experiencing a lecture using evidence-based slide designs. Notice the difference in the two slides that show the same result. The top slide has a title, whereas the bottom slide has an assertion headline. The top slide has the traditional text bullets whereas the visual evidence carries the day in the bottom slide so that the auditory channel of the learner is open to focus on what the speaker is saying. There is another cognitive-load-reducing trick in the bottom slide: Notice how the default PowerPoint graph legend in the top slide is replaced by direct-labeling of the data representations in the bottom slide.
At this point, you might be ready to complain, as I commonly hear, that the assertion-evidence format does not provide the information that the students will want after the lecture, through the common practice of posting the slides or the convenient PowerPoint Handout to a webpage. In my opinion this misses the point. Learning during the presentation is a different learning experience than self-paced reading. If the intention is to promote learning during the presentation, then the presentation must be optimized for learning. Otherwise, if the intention is to provide illustrated text for students to read on their own, then provide that text instead and forego the presentation altogether. In those common situations when it is deemed beneficial to have text representation to study after the presentation, there are two solutions: (1) Provide text explanation in the notes window beneath each slide and then upload your file in Notes Pages format; (2) provide separate text-rich handout materials, perhaps based on your lecture notes and including images from your slides. Option 1 is particularly attractive to faculty who revise existing bullet-ridden presentations, because that text information is simply cut out of the slide and pasted into the notes window.
Now … are you still wondering about what the best slide background should look like? Mayer’s principle of coherence offers some value to this question by pointing out – and this shouldn’t really be a surprise – that the slide shouldn’t contain anything that isn’t specifically and explicitly relevant to what you are saying and what the audience is supposed to learn. Your eyes automatically scan everything on the screen and working memory expends brain power to make sense of your institutional logo, the mountainous landscape outline at the bottom of the slide, or the rays of light emanating from a corner as if to imply divine inspiration for the slide content. None of this is relevant to learning and adds cognitive load. Unless your lecture is about art or graphic design, leave out the fancy colors, fonts, logos, patterns, and unnecessary animation. When it comes to color schemes, the research is quite clear that text and background must be strongly contrasting to be legible. Research regarding multimedia display generally and PowerPoint in particular supports that black text on a white background produces the greatest legibility. And, the same research points to a white background being viewed as most pleasant to the viewer. I wonder if claims that blue backgrounds are more appropriate – and blue was the default background color in early versions of PowerPoint – is a legacy of preference of increasingly older audience members. Perhaps we are nostalgic for the days of 35 mm-slide presentations where text and graphic slides were made by contact printing of film negatives onto a transparent diazo sheet, typically generating white text and lines on a dark blue background. Black on white, however, is what the eyes and visual cortex are used to when processing text; unless you routinely read books with white text on blue paper.
If you value being an evidence-based educator, think “assertion-evidence” the next time that you make a PowerPoint presentation. Diminish cognitive load to enhance learning during the presentation. Start with blank, white slides (or download the assertion-evidence template) and write the take-home point as the headline sentence at the top of each slide. Then, think about the visual slide element that either serves as evidence for that headline assertion or is a concrete visualization of the statement that enhances understanding. Worried about where to find those images? Consider your texts or even using a quick GoogleTM image search, which will likely generate dozens of possibilities. Your learners will learn and they won’t be gunned down by bullets – probably the most common cause of death by PowerPoint.
By Gary A. Smith, Assistant Dean of Faculty Development in Education and Director, Office for Medical Educator Development, School of Medicine, University of New Mexico. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.