In this sixth post in this series, looks at multimedia design principle of 'redundancy', as researched by Prof RE Mayer, J Sweller et al.
This principle says that redundant information interferes with learning and material being retained in long term memory. Giving people more information, does not necessarily increase their ability to remember the key learning points.
You can apply this principle by carefully synchronising what you say to your audience with what you show them. If you show too many words your audience is forced to make a choice between listening to you, or reading your slides. Whichever they choose, they will be distracted by the other, reducing the likelihood of your message entering their long term memory.
Likewise, if you want them to read an explanation on your slides then let them do just that. Turn towards your slide to direct your audience's attention away from you and to the slide, read the explanation silently yourself, count to ten, and then face your audience and re-engage them.
The rule of thumb is: "If you show it, don't say it, and if you say it, don't show it".