From the linked post—
The brain cannot do two things at once and do them equally well. When it comes to presentation design, we can’t read text on the screen and listen to the speaker while retaining all of the information. It can’t be done.
We are incredible at remembering pictures. Hear a piece of information, and three days later you’ll remember 10 percent of it. Add a picture and you’ll remember 65 percent.
Those classic PowerPoint slide decks with a headline followed by multiple bullet points of long phrases are the surest single way to lose an audience’s attention altogether…when we see speakers come to TED with slide decks like this, we pour them a drink, go and sit with them at a computer monitor, and gently ask their permission to delete, delete, delete.