Are you convinced that Mount Everest tastes like strawberries? Or that Friday is a deep green colour? Does hearing your friend Dave’s name make you wretch? If so, you might be entering the baffling world of synesthesia.
Synesthesia (synaesthesia in British English) is a neurological condition whereby one’s senses literally merge. It means ‘joined perception’ and can cause names to have a particular taste, letters to have a particular colour and a whole host of other sensory fusions.
It may sound more like a psychedelic experience in a drug-induced haze but this is a sober reality for a number of people. Some of the most famous creative types of our times have been diagnosed or suspected to have synesthesia. Marilyn Monroe was described by the biographer Norman Mailer to have a “displacement of the senses which others take drugs to find… she is like a lover of rock who sees vibrations when she hears sounds”.
Stevie Wonder reportedly has sound-colour synesthesia whereby even though he is blind, he ‘sees’ the colour of the music. This added sensation is not restricted solely to arty types, however. Richard Feynman, the excellent Nobel Prize winning physicist, claimed “When I see equations, I see the letters in colours”, before quipping, “I wonder what the hell it must look like to the students”.
Estimates put the number of synesthetes at between 1 in 200 and 1 in 100,000 (which basically means we really don’t know how many people experience synesthesia). Some even claim it could be as high as 1 in 23! If any of this sounds familiar to you, you can test whether you may have synesthesia here.
There is a lot of fascination from scientists into this condition. The organisation of the senses is seen to play a major role in formation of memories. When you form a memory of a person, you link the information from multiple senses. The sound of their voice, the colour of their hair, the letters of their name all form your memory of that person. But for most of us, these senses still exist as separate aspects of our memory of that person. You don’t intrinsically link the letters of their name to their hair colour.
Synesthetes have secondary sensory experiences that are completely involuntary. Some synesthetes say that the colour of someone’s name is actually how they remember them. They may remember the name Dave by the colour orange more than the letters of the name.
This is where the science behind it all comes in. Sensory information should be contained separately but able to be integrated at will. Different sensory information is processed in largely the same way but in distinct sensory regions. You can see below the various parts of the brain that are responsible for the different senses. As you can see they are spatially separate. The beauty of the brain is connecting this information as and when it is needed.
What appears to be the case in synesthetes is that these sensory regions are intrinsically connected. For example, sound-colour synesthetes seem to have more activity in colour-processing regions of their visual cortex (known as area V4) while listening to sounds. Instead of distinct pathways being linked at will, it could be the case that these two systems are bound together and stimulation of one sense also activates another.
It is interesting to be able to see these differences in the brains of synesthetes. What is not very clear, however, is why synesthesia is around at all. Does having synesthesia benefit you in any way? It appears that actually it might.
Synesthetes have been known to be better at remembering phone numbers, for example, suggesting they may have better memories. Letter-colour synesthetes have also shown they can be better at discriminating between different colours, whilst hearing-motion synesthetes are better at visual tasks. So could this be a rise of the superhumans – an evolutionary advantage to be able to process more sensory information than the rest of us?
Further research into synesthesia will not be a purely academic exercise but will contribute further to our understanding of the human brain. How the brain links information together on request is one of the major mysteries of neuroscience, a point focused on in Obama’s BRAIN initiative. As synesthetes show remarkable differences in how they integrate information, it will be fascinating to see whether they can be the valuable subjects to advance our knowledge of the brain.
Post by: Oliver Freeman @ojfreeman