I recently spent a weekend camping with some kids. I don’t remember exactly what we were talking about when I brought this up, but I mentioned that I could convince someone that their nose was 2 feet in front of their face. It’s a pretty cool demonstration I read about in the book Phantoms in the Brain, by V.S. Ramachandran & Sandra Blakeslee (1998).
As a neurologist, Ramachandran works with people who have some really fascinating conditions. Individual case studies are pretty important to the field of neurology, and form the basis of the book. Observations made from those with atypical brains inspire hypotheses about typical brains function. Phantoms in the Brain focuses on sensory processing and our perceptions of not only our world, but also our self-perception. A few experiments included in the book, make the material personally relevant to the reader. This includes convincing someone that their nose is not where it actually is.
Three people (who are OK with an invasion of their personal space) are needed: the experimenter, the subject, and someone to be a decoy nose. The subject closes their eyes and point a finger. The experimenter tells them, “relax your arm and let me move your hand, I’m going to touch your nose with finger”. The experimenter won’t be dong this, instead they guide the hand of the subject to touch the nose of the decoy person. At the same time, they touch the nose of the subject with their own hand.
The subject’s brain is obviously not going to be fooled by this instantaneously. But after about 30 seconds of a sequence of random taps and strokes (the more random the better) something awesome will likely happen. If the illusion is successful (it doesn’t work 100% of the time), their brain will conclude that the reason they feel the same pattern on both the tip of their finger and their nose, is they are actually touching their own nose, and therefore that their nose is out away from their body where their finger is.
Reactions to this illusion vary: some people hardly react, most will say “whoa” or gasp, and others feel downright traumatized by the experience. It’s really amusing to watch a subject still wiggling their nose 10 minutes later to check it’s still there in its proper spot.
So read a good book this summer, just for fun and interest. Oliver Sacks was another neurologist who wrote many books (including The Man who Mistook his Wife for a Hat). If you prefer to listen to stories instead, both Ramachandran and Sacks have been guests on the radio show/podcast Radiolab, including an early episode “Where am I?“.
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