Even if you’ve seen this beore, it’s worth seeing again. The following link is to a video of two teams (white and black) playing a ball game. Your task is to watch the white team and carefully count how many times they pass the ball (concentration is important):
Now, watch it again, paying attention to everything on the screen. Most people will notice something they did not see the first time when they were just watching the white team. (This is hard to do in a blog, without spoilers!)
This gets back to my previous posts about how attention affects how you perceive what you see. The professor that designed this, by the way, is Daniel Simons of the University of Illinois. He’s produced a great deal of fantastic research; this is just one example. In a random small-world coincidence, he was the previous tenent of the office suite I worked in last year at Harvard.