Yeah, there was a BBC documentary where they repeated it for the camera...it was really quite amazing to see that, even though the guys looked really quite different, nobody noticed a thing. It might be interesting to note though, that they were both wearing safety helmets. It's probably things like these people notice, not random faces.

This experiment doesn't prove anything, because its design isn't culture-free.
Everyone who has ever seen Monty Python knows exactly that the British are just, well, british. What should they do even if they noticed the change? Noone expects them to say things like "excuse me, weren't you a completetly different person just a second ago?" That's embarrassing!

Here in the US there is a short video (a couple of minutes maybe) which is shown to audiences. The audience is told to pay close attention and remember as many details as possible, as they will be asked questions afterward. The video shows a person entering a room and approaching a counter, and then apparently asking the counter person a question. The counter person bends down behind the counter (out of sight) and then (apparently) stands up again. Only it is a different person this time. The majority of the viewers (I hate to say it, but myself included) failed to notice that there was a different person behind the counter. This experiment gives the same results as the one above (but without helmets nor culture problems).

This kind of cultural experiment is fascinating. I like the new blog layout. Is it part and parcel of your "experiment" article to see if anyone notices the change to "The Aardvark Speaks"?

Some time ago, I received a set of animated pictures that gradually changed over time, and it took everybody several passes to realize what the change actually was. And I assure you, the picture was decidedly altered afterwards.

Also, the brain tends to edit memories. Basically, the more often you reminescence what happened the more you are editing and overlaying your original memories with other material. There was a fascinating experiment what people were equipped with head-mounted videocams walking around a city, and asked afterwards to describe what they remember seeing. The stories changed each time they were told to tell about their walk. When they were finally showed what they actually saw vs. their recollection, it was quite a shock. People had a completely different recollection of their walk around the city than what was recorded on video.