From long before the days of the sabre tooth tiger, we have been programmed to put our visual senses on high alert when something moves. That hasn't changed. Advertisers know it and ruthlessly exploit it - it's hard to find a TV ad that doesn't have something moving or changing all the time.
Here's the point for PowerPoint presenters.
A new slide briefly deafens the audience
An audience that sees a change on the screen is effectively deaf for anywhere from one to five seconds depending on the visual impact of the slide. And that's a problem for PowerPoint presenters who keep right on talking through the changes.
Here's what to do about it.
Take your audience with you when you change slides
On each change of slide, look at the screen with the audience in silence. How long? It's a judgement call which you make by pretending that you - like the audience - are seeing it for the first time. How long would it take you to absorb (roughly) what it's about?
The same applies to each animation, but of course they're likely to need less silence than a complete new slide - typically only a second.
Pre-announcing each slide
One more thing. If you really want it to look competent, pre-announce each slide. So here's a summary:
- pre-announce the next slide. "Now let's see...etc"
- click the button and quickly look at the screen with the audience in silence.
- speak to the audience, adding value to what they can see for themselves, glancing occasionally at the screen.
You might also want to look at PowerPoint tip 1.