Invisible Gorilla: selective attention

I recommend  showing this video to a group or class ,and doing it this way.
Show the first  (Regional Emmy winner) video  below starting at 4 second mark, telling the group that no one should say anything, or make any noise, while watching; just concentrate hard on following the instructions:



 You can see why calling it the "Invisible Gorilla" test might jinx things(:

Here is the backstory:
More? Click: theinvisiblegorilla.com/

How about this version:
\ TED Talk   by Daniel Simons:

Christopher Chabris'  talk at Google about Invisible Gorilla:
 Here's a great spoof version:

Of course people have made endless variations:

YouTube search: "selective attention"
YouTube search: "invisible gorilla"