Phantom limbs and extra noses

4 July 2013

 A mirror box experiment at a Barbican 'Wonder' event.
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A mirror box experiment at a Barbican ‘Wonder’ event.

On Friday 5 July, as part of  Wrong! A carnival of human error at Wellcome Collection,Matt Longo and Elena Azañónwill be presenting perceptual illusions that play with the body’s sense of itself. Here they explain how even your own limbs might not be telling you the truth…

No matter what we do, no matter where we go, our body is right there with us. Our body is the most familiar object we encounter. As William James wrote, it’s “that same old body always there”. Surely if there’s anything we know like the back of our hand it’s… the back of our hand.

Research in psychology and neuroscience has started to revolutionise how we understand the way we experience our body, and how the body is represented in the brain. Along the way, this research has revealed some surprising findings, showing that in many circumstances we appear to have remarkably poor knowledge about our body. Moreover, our perceptual experience of our body can be altered by simple sensory inputs.

For example, anyone unfortunate to have received dental anaesthesia will know that it makes it feel like your mouth has become enormous. Effects like this suggest that the signals the brain receives from nerves from all over the body continuously shape our mental picture of our body, what is commonly called the ‘body image’. Other illusions make people feel like their waist is wider or thinner than it really is, or even that their nose is getting longer like they were Pinocchio!

Recent research has begun to quantify effects like this and to investigate the underlying processes in the brain. Both of us are currently researching particular aspects of this area: Matt is investigating the mental representation of our body and how this shapes perception, and Elena is interested in the way we perceive touch when the body adopts different postures.

On July 5, as part of Wrong! at the Wellcome Collection, we will be demonstrating some of our favourite perceptual illusions. You’ll be able to try out the ‘mirror box’ that allows amputees to ‘see’ their phantom limb, or to experience the feeling that your own face has become merged with somebody else’s. You can sense how a prosthetic hand really feels like part of your body, or even experience having two noses. We’ll explain how scientists are using these illusions to reveal how the mind represents the body, how different senses such as vision and touch become integrated, and how these processes are implemented in the brain.

We hope to see you there.  Don’t forget to bring your body!

Wrong! is at Wellcome Collection on 5 July. Matt Longo is a Senior Lecturer in the Department of Psychological Sciences at Birkbeck. Elena Azañón is a Marie Curie Research Fellow in the Institute of Neuroscience at UCL.