Let’s say you’re using the default template in PowerPoint, and you completely fill in the field with bullets that says “click to add text”. That field alone holds about 80 words, and the average reading speed is 250 words per minute. So, if you develop 40 text-heavy slides for a 40-minute presentation, people will miss about 13 minutes of your talk (that’s one-third of it!) just because they’re too busy reading your slides to listen to you.
Keep your presentation slides simple because research proves that people learn more effectively from multimedia messages when they’re stripped of extraneous words, graphics, animation, and sounds. The extra artifacts actually take away meaning because they become a distraction. They overtax the audience’s cognitive resources.
Each slide should pass the glance test: People should be able to comprehend your slide in 3 seconds. Think of your slides as billboards. When people drive, they only briefly take their eyes off their main focus, which is the road, to process a billboard of information. Similarly, your audience should focus intently on what you’re saying, looking only briefly at your slides when you display them.