I read the book several years ago, and one observation he made particularly sticks in my memory.
He explains that when he’s doing a sleight-of-hand trick, he directs the attention of the audience where he wants it to go, and away from the trick he’s doing. He stays relaxed and casual, and with his story, voice, pacing, and actions, takes the audience where he wants them to go.
To my surprise, Derren Brown noted that his tricks worked best with the most engaged audience members, the ones who were hanging on his every word and scrutinizing every move he made.
He explained why:
It is generally the most disinterested spectator who is hardest to fool. When I performed this kind of magic for groups at parties, it was the peripheral punters, stood on the sidelines with folded arms, half in conversation with each other, who were the danger. If they were not paying attention, I could not bring them into the game. They watched less, but they saw more.
I found this observation astonishing. These audience members watched less—they paid less attention—and for that reason, they saw more.
In this exercise, a viewer is told to watch a video closely and keep count as a group of players pass a basketball among themselves. The astonishing thing is that this viewer won’t notice when a person in a gorilla suit walks through the center of the action. You can try this experiment for yourself, online! You’ll see that the harder you look, the more you miss. Even if you know about the illusion.
These two examples illustrate a point: that sometimes, by pulling back our focus, and taking a wider view instead of scrutinizing specific details, we can see more, and that when we pay too much attention to something small, we may miss something big.