I was talking to a friend today about how we explain that when you look at a scene, what you see depends to some degree to what you do.  There are lots of examples of this and we were trying to find one most people would get. My suggestion was to use the idea of sleight of hand and a magician. When we see a magic trip we wonder, if he's good, how it was done. Another magician see that and also the presentation. I had this happen at a tradeshow where we had a magician working as a draw. We got talking and he asked me to show him something. I did a simple coin trick and he not only knew how I did it but gave me advice on showmanship, presentation, and set up.

So as the example, think about how the Amazing Randi has exposed psychics who have successfully tricked scientists into believing that they are really using ESP. The scientist tends not to believe people cheat and lie (something that to my mind explains polling data BTW) as matter doesn't. The magician not only bases his livelihood on deception, but develops it to an art form. Hence he instinctively looks for the trick. Similarly in the Black Swan, the author talks about what happens when Fat Tony, a streetwise trader, and a professor of statistics watch a coin get flips and gives 99 heads out of 100 flips. The statistician talks about long random runs, Fat Tony talks about a weighted coin.

So when someone asks what you see...