A woman with a type of synaesthesia experiences huge bouts of laughter when she sees other people being tickled. Researchers studying the phenomenon say her condition hints at how we all feel empathy.
Known as 鈥淭C鈥�, this woman has mirror-touch synaesthesia, a condition that makes people feel sensations on their own body when they watch other people touching things. This is caused by mirror neurons in the brain, which act in the same way whether we watch someone else being touched, or are touched ourselves. Normally, when we watch other people being touched, veto signals from elsewhere in the body help us to distinguish between the self and other.
But these veto signals are weaker in people with mirror-touch synaesthesia, giving the brain a blurred sense of self. To investigate how this relates to tickling, Vilayanur Ramachandran and at the University of California, San Diego, set up several tasks for TC, such as spontaneously tickling her, getting her to watch others being tickled, and seeing how much she laughed at funny situations.
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Empathy spectrum
They found that TC didn鈥檛 generally laugh any more than a non-synaesthete. However, when watching someone else being tickled under an armpit, TC burst out laughing and tried to make it stop by placing her hand under her own armpit 鈥� which seemed to help.
When TC watched a video of herself being tickled, it 鈥渓ead to an apocalyptic seizure of uncontrollable laughter,鈥� says Sellers 鈥� as though she was getting a double dose of tickling.
The interaction between how we represent our self and the other in the brain is thought to be important to how we all experience empathy, says , at Goldsmiths, the University of London. 鈥淩ecent theories argue that [this interaction] may explain individual differences in empathy.鈥�
Sellers agrees. She says that the ability to simulate other鈥檚 states in your own body is not a unique phenomenon but an extreme example of something that we all do. 鈥淲e all sit on a spectrum of empathy,鈥� she says.
Neurocase
