You probably wouldn’t have much difficulty if I asked you to imagine a bad PowerPoint presentation. Nowadays one sits through so many of them that confusing, boring or annoying slide shows are sometimes perceived as the norm rather than the exception. A research team from the universities of Stanford, Amsterdam and Harvard headed by Stephen Kosslyn explains how to do it better. In order to reap off the benefits and avoid the pitfalls of visual aids, presenters should think about avoiding weaknesses of human information processing and play on the strengths of such processing.
Kosslyn and colleagues see the task of the audience viewing a PowerPoint presentation as composed of three steps: a) information needs to be acquired, b) information needs to be processed, c) information needs to be connected to knowledge. They derive eight principles that a presenter should follow based on this analysis.
a) encoding, i.e. acquiring information and turning it into a usable form
1) Discriminability: make it easy for the audience to discriminate colours, letters, sizes, line orientations etc.
2) Perceptual Organisation: group things effectively in the visual space you’ve got
3) Salience: use large perceptual differences to guide attention to what is IMPORTANT
b) working memory: holding information in mind in order to integrate it online
4) Limited Capacity: understanding breaks down once too much information has to be retained
5) Informative Change: when something perceptual changes, this change has to mean something
c) accessing long term memory: connect the new information with knowledge in order to extract meaning.
6) Appropriate Knowledge: avoid as much novel concepts, jargon or symbols as possible
7) Compatibility: the meaning of a message needs to be compatible with its form
8) Relevance: provide neither too much nor too little information
These principles may look very obvious but they are frequently violated. From an internet sample of slide shows it became clear that on average a PowerPoint presentation violates six principles at least once. Some principles were nearly always ignored: 1) discriminability, 4) limited capacity, 5) informative change.
Now, one may argue that these principles are simply guidelines that lay people are unaware of. No wonder they get violated. However, in a subsequent laboratory experiment participants were 80% correct in choosing a non-violating slide and rejecting a bad one. Moreover, when asked to say why one slide was better, more than 80% of the correct choices were appropriately justified.
So, this study is about what one already knows but still ignores when designing a slide show. The authors use a backdrop of psychological literature to predict what sorts of principles should guide PowerPoint presentations. What they, unfortunately, fail to do is to empirically test each principle’s impact on presentation understanding and memory. As such, this study simply presents a set of guidelines, says that presentations usually violate guidelines and that most people are aware of these violations. How important the guidelines are to begin with remains unclear.
The main take-home message is that the more work a presenter does for his/her audience, the more the audience can tune into the content of the presentation. For my part I am always guided by a more memorable principle:
Look around the room and search for the newbie or the bored one or the least intelligent listener. S/he is your target audience.
For a complete list of useful rules which may help you and especially your audience, see the appendix of Kosslyn and colleagues’ paper.
Kosslyn S.M., Kievit R.A., Russell A.G., & Shephard J.M. (2012). PowerPoint® Presentation Flaws and Failures: A Psychological Analysis Front. Psychology, 3 DOI: 10.3389/fpsyg.2012.00230
1) Photo credit: Wikipedia