Claire Duffy's blog about public speaking and communication (in real life). Speak well, do well!
It’s a theory of instructional design developed by John Sweller at the University of New South Wales, and he caused a ruckus when he said PowerPoint is a disaster.
To understand why, you need to appreciate the effort an audience makes when they listen to you.
The basic idea is that our working memory is limited. If what we are learning from presents information in ways that make best use of our ‘cognitive architecture’, we will be able to learn well. The reverse is also true. Present us with information that doesn’t fit easily with our cognitive structures, and learning will be harder.
The brain has two pathways for processing information. The auditory cortex is for language – both spoken and written.The visual cortex picks up the images, and works on the lines and features to assemble the words that are being read.
A PowerPoint presentation asks an audience to do two things, read the slide and listen to the talk, at the same time. Audiences looking at busy, dense slides soon suffer overload of the language areas, while the visual cortex has little to do. If you’re the speaker, you are literally wasting your breath while they decode the written information in front of them. This article explains it in more detail.
In fact, any material (pictures, sounds or information), which is not relevant to the topic, harms learning. Flip it, and removing extraneous information from a screen increases learning.
In reality, good presenters know that students and audiences require variety to keep their attention. ‘Information only’ presentations, lectures and lessons are dull. I am always telling people to use their voice like a paintbrush to colour and lift their words – it’s more interesting to listen to. Teachers are always mixing up ‘listening’ and ‘doing’ activities to keep their students engaged. The challenge for presenting lots of information in PowerPoint is to have enough of these diversions to be stimulating, but not so many that you put the learning process to death.
So – what to do ?
First, get this guide to making a good presentations. You should get rid of visual clutter and make your slides sparse. This reduces the workload for the audience, and leaves them with spare mental ‘bandwith’ to process what the speaker is saying.
Second, be sure to choose a communication channel that’s best suited to your material. A slide is not the right place for lots of statistical information – it makes no more sense than publishing a novel via sms. If you have a lot of data, move it OFF the screen, and into a handout .
Garr Reynolds – author of Presentation Zen, says limit it to one idea per slide. He says a slide is like a billboard, you should pick up its meaning at a glance. Nancy Duarte, author of the best selling book Slideology has similar guidelines. Both have books and websites that give excellent guidelines on designing beautiful slides. In my experience this never fails. Look at these makeovers and you’ll see the difference.
Thanks to Olivia Mitchell for her excellent posts and graphics on this topic on Speaking About Presenting.