Let the primary use of your presentation dictate your slide design philosophy.
Slide decks are usually the end deliverable of consulting engagements, so consultants must prepare excellent documents to justify their huge fees and looking for inspiration in how strategy consultancies prepare effective presentations can be useful. But consultants are not the best at integrating images and generating emotions in their presentations so you can also find good inspirational material in design-centric approaches.
Understand the two extremes and decide where you need to be. There are two potential uses for a presentation: serving as a visual aid during the presentation or as a record for future reference. Knowing the primary use of your presentation is critical to guide the design of your slides.
Take a look at the extremes. The “zen” model is perhaps the best example of the extreme visual support slide design: a photo and, sometimes a key word. On the other hand, management consultancies have mastered the use of presentations for establishing a record.
In the figure above, the picture on the left is from Garr Reynolds. Garr’s approach, as explained on presentationzen.com, uses lots of images and very little text. His emphasis is much more on the emotional side of communication than on logic. This is consistent with Nancy Duarte’s approach to slide design: both use so little text than, without a presenter, you can’t understand the main point of some slides.
The slide on the right is from a presentation to the French government by BCG. There are no emotions here, it is entirely geared towards logic. Also, compared to Garr’s slide, the message is much more complex. But it allows to capture many more details and nuances.
Even with the zen approach, you should ensure that your tagline summarizes your slide.
In a typical zen slide, the photo and the text are enough to give an idea about the point of the slide but not certainty, so your audience has to guess. Of course, if a presenter is there to tell them what his conclusion is, this might be enough, but that restricts the presentation to being only a visual support and you still risk to lose your audience if they just happen not to pay attention when he explains the “so what?” of the slide. Instead, all it would take to make the slide a powerful visual support and a good future-reference document is to include your main idea on top, which shouldn’t add more than five to ten words to the slide. Why wouldn’t you? (For more on this assertion-evidence structure, see Alley, referenced below)
The zen and the consultant slides are two extremes of a spectrum. Both are excellent at what they do; they just happen to use Powerpoint to do two very different things, just as a clarinet’s use in a symphony orchestra is different than in a jazz band.
Aside from personal preferences, the key to good slide design is optimizing it for the specific use you want from it. So question your motive and pick the best option for you.
Learn more: Duarte’s (1 & 2) and Reynolds’s (1 & 2) books are good references for slide design from the zen standpoint. Also, Abela’s book makes a fantastic contribution for more technical presentations (see his blog here).
Alley, M., et al. (2006). “How the design of headlines in presentation slides affects audience retention.” Technical communication 53(2): 225-234.