Tuesday, August 12, 2008

Now you see it. Now you see it. Now you don't

Now you see it. Now you see it. Now you don't. No, I'm not stuttering. That sentence more accurately describes what happens when the visual cortex pays attention to sudden changes in the environment, according to Dr. Susana Martinez-Conde of the Barrow Neurological Institute in Phoenix. After the sudden disappearance of an object, an after-image of it lingers behind for a very short time, but just long enough that the brain is distracted, and that distraction provides the cover for the magician's manipulation which the human eye is unlikely to see. Benedict Carey's article in today's Science Times is about a paper in Nature Reviews Neuroscience written by two neuroscientists and a magician, that explores how the magician exploits the compensatory strategies our brains have evolved to overcome the limits of our perceptive and attentional systems.

...the brain focuses conscious attention on one thing at a time [not everyone agrees with this], at the expense of others, regardless of where the eyes are pointing. In imaging studies, neuroscientists have found evidence that the brain suppresses activity in surround visual areas when concentrating on a specific task. Thus preoccupied, the brain may not consciously register actions witnessed by the eyes.

Perception is my research area, and performing on stage is my former life but my very first work when in my teens was as a magician. I had a business doing shows for kids' birthday parties and the like. Perhaps I really have come full circle. There are six film clips in the supplementary section of the Nature Review Neuroscience article of magicians doing various tricks that illustrate the phenomena discussed in the article. Enjoy the show.


Anne Camille said...

Fascinating! I'll have to watch these tomorrow (at my office where I have better bandwidth!). One of the things that amazes and puzzles me is how, when you know that the magician is exploiting that your brain is focusing on one thing -- and you try to focus on the other, you can still miss it. Our brains are so geared (out of habit? experience?) to what we expect to be happening, that our focus is still led in the direction to see the 'trick' instead of how it is performed, I suppose?

Ted said...

Cam - In some cases it is habit and experience, which can be overcome, but in other cases they can exploit something that is hard-wired, in which case their isn't anything we can do!