When you and a friend use this hands-on exhibit…one person will place their hands on either side of a mirror and keep watching the reflection of their hand in the mirror.
The second person will brush or stroke the other person’s palms in a particular pattern, so the other person feels their hand being touched, but not see anything touch their hand!
When our brain gets mismatching visual and touch signals, it can feel confusing, even freaky!
Your brain can adapt and remap what it accepts as belonging to your body, what is alien and how your body is positioned in space. This is known as body schema.
Some sportspeople start to perceive their sporting equipment (such as a tennis racquet) as being an extension of their own body.
People who feel pain where their amputated limb was once positioned are said to suffer from phantom limb syndrome.
Similarly, some people who have intact arms or legs feel such a strong rejection of a limb that they need to have it surgically removed.
When using this exhibit, some people start to assume that their hand’s reflection in the mirror is actually their left hand and not simply a reflection of their right hand.
So, when they can see that nothing is touching their ‘left’ hand, but they feel something touching their ‘left’ hand, it can feel unsettling.
It may also generate the sensation of a phantom limb in people who have two complete arms and hands. Phantom limb sufferers feel that they can move their ‘phantom’ but the phantom limb feels ‘paralysed’ in a cramped and painful position (even when the sufferer can see the limb’s not there).
Our brains process matching sensory signals every day, such as simultaneously seeing and feeling something touch our hand.
This exhibit (and a therapeutic mirror box) provides your brain with conflicting feedback from touch and visual channels. Your body schema gets confused and your brain finds it difficult to calculate where your (hidden) arm is located.
An area of your brain called the somatosensory cortex is like a strip that runs over the top of your head a bit like a head band. This area handles tactile sensations from your arms and legs as well as your face.
Body schema maps of your limbs are malleable and changeable (neural plasticity).
Research is still being done on why this feeling or paralysis occurs. Phantom limb paralysis develops because every time the patient attempts to move the ‘paralysed limb’, the patient receives sensory feedback (through vision and proprioception) that the limb did not move, which is translated and reinforced as ‘paralysis’.