Like many people I attend a lot of meetings, events, and I still attend lecture for classes I’m currently enrolled in at the University of Vermont. In these environments a large volume of information is presented and retaining that information is sometime hard. Scientific research has a good explanation why retaining information is so difficult. A psychological phenomenon known as change blindness dictates that humans can hold onto visual information for about a fractional of a second. For sounds, humans can remember about three seconds worth of information using their auditory loop, a type of memory. 
In his book, “Smarter Thinking” Art Markman introduces a concept known as the Role of Three which stipulates that we remember about three distinct and independent pieces of information about an event. He uses a baseball game as an example, when we go to a baseball came (which I coincidental did a few weeks ago) we remember about three things from the game. In my case I remembered the two rain delays, people being excited when the camera panned on them, and the organ player.
Markman gave three tips for making effective presentations, so people remember what you want them to:
- Start all presentations with an outline and try to limit the outline to three main items, if you can’t group similar items
- During the presentation try and stay focused on the three main items, so people remember the message you are trying to convey
- At the end of the presentation, summarize your three key points
 Smarter Thinking, Art Markman, Penguin Group 2012