Looking Out To Sea

Monday night’s Cafe Scientifique was magnificent and I feel very sorry for all those people who didn’t come. It was about synaesthesia and given by Julia Simner from Edinburgh University.

Synaesthesia seems to be about as fascinating a subject as anything to study, with all sorts of revealing facts about language, learning and development, neuroscience, memory and childhood lifestyles being wrapped up in the heads of synaesthetes.

So what is synaesthesia? Essentially, it is “creation” of sensations when unrelated parts of the brain are activated. For instance, tastes might also give the sensation of texture on the back of the hand, or words might activate tastes or colours. The pairings are related to the proximity in the brain for the different sensations — associated pairs always turn out to be adjacent in the brain. For a particular stimulus the sensation will always be the same for that person — “William” will always taste of potato for that person.

So, some interesting facts:

• If you get a colour sensation when reading letters then the colours will not be arbitrary, though any two synaesthetes may disagree on the particular colours. The commonest letters and commonest colours often pair up: ‘A’ is often red and so on.
• Forcing non-synaesthetes to choose colours for the letters of the alphabet tends to produce very similar links between the commonest colours/letters.
• Word/taste synaesthetes have a similar distribution of tastes, according to their childhood diet. So there will be many sweets and sweet-flavoured words, and few or no alcoholic ones.
• Synaesthesia is a heritable condition because it is caused by a hyper-connecitivity in the brain. I asked whether this has any effect on prevalence of epilepsy, though she didn’t know. She was aware that many synaesthetes seemed to complain of migraine.
• The extra sensations can be useful in test situations — letter-colour synaesthetes tend to perform better in spelling tests. People who see colours when hearing words are better at transcribing voices when listening to noisy signals like a badly tuned radio.
• Most synaesthetes seem to have only one form of synaesthesia though it can happen that many sensations can kick off many others, which can be quite discomfiting.
• Some synaesthetes see a ‘ticker tape’ transcription in front of them as they hear voices — literally like their own private subtitles.

There were loads of other fascinating things that we spoke about that evening. To get a little taste of the subject why not read up on Dr Simner’s appearance in Nature — she was on the podcast which has a transcript online as well as in the journal. (I think I made her day by mentioning that I remembered her on the podcast from two years ago. She thought I was the only person who must have listened to it. So go listen!)

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