You don’t even read the slides you are reading. Part of your brain soon recognises that it isn’t possible to read a whole slide and that the important information is contained in the title. The bigger bulletpoints contain something of value with the least important information at the bottom. Consequently we scan a slide looking for the important data. This is known as F-scanning. Scientific studies using eye tracking devices reveal how this occurs. The end result is that not all the data is read.
The science shows that even all the effort put into reading and not listening goes to waste as not all the information is “downloaded”. Presentations fail because science.