When I was about 10 years old I remember asking my classmates (in anticipation of later doctoral research) what colour each of them thought the number 9 was. Then, as with repeated experiments over the years, most of them looked blankly and said they had no idea what I was talking about. But if I persisted – suggesting they imagine the numeral in their mind (not that I would have used the word ’numeral’ back then but whatever) – they usually coughed up an answer.

I could play the same game with days of the week, letters in the alphabet, even places they may have been. I remember quite clearly thinking this was fascinating and wondered why no one else had thought of the idea before. It was only much later – 20 or 30 years later – that I came across the term ‘synaesthesia’ (or synesthesia if you’re on that side of the pond) and realised there was a whole body of thought around the concept, emanating from research into sensory neurology and psychology.

But researchers usually describe synaesthesia as a kind of gift – an almost mystical form of meta-perception bestowed on a lucky few – as rare as one in 2 000 and as frequent as four or five percent depending on the rarity of the specific form. I beg to differ. I’m convinced (and I’m not alone) that almost everyone has at least this basic form of cross-sensory perception. And many of those, albeit a much smaller pool, experience dramatic associations powerful enough to bring them to tears, or invoke a distinct taste or smell.

Common Colours

The kind of everyperson experience I’m referring to is variously known as letter-colour or ‘grapheme‘ colour synaesthesia, or even Ideasthesia – a kind-of competing school of thought which suggests the induced sensory perception relates to the idea of the word (or letter or number) rather than purely on the basis of the thing itself. Personally, I don’t think that one holds up very well against my schoolyard survey (now more of a party trick I don’t seem to tire of) but it’s a thought…

Anyway, this lesser, common synaesthesia is considered passive or ‘associative’ and doesn’t quite carry the same cachet as the more exotic forms of active or ‘projective’ synaesthesia which manifest in taste (lexical-gustatory synaesthesia) or auditory hallucination and which guarantee a more receptive audience at the salon. But those aware of it in themselves or their subjects still regard it as unusual. Indeed they usually keep quiet about it lest they be taken for some kind of unwitting oracle…

More recently, I asked some friends the usual questions and one of them reacted in horror when we got to the number 10. ‘Ugh’, they said, ‘what a horrible number!’ When pressed they couldn’t really explain why (or didn’t want to) but they insisted that 10 was ugly and somehow unseemly. Odd for sure, but no more, I suppose, than my son’s aversion to flour (on a loaf of bread for example), my daughter’s fear of torn paper, or even my own, slightly embarrassing, dislike of… Baking paper! Don’t ask…

Colour Decoded

There is some debate in the research community as to whether the synaesthetic association of, say, colours and numbers is innate (to the individual, they’re clearly not universal) or acquired in childhood (or later) through learned association. Readers of a ‘certain age’ will remember the brightly coloured Cuisenaire Rods popular with school teachers in the 1960s and 70. The rods were small rectangular blocks of different lengths used to demonstrate mathematical relationships by allowing children to see and touch the representative ratios and values the rods represented. A 3cm rod was light green, for example, a 10cm rod was orange. I wasn’t particularly adept at mathematics myself but I did love those rods…

My first career (such as it was) was in electronic engineering and part of my training was to learn to decode the cryptic colours on the side of ‘resistors’ – those small electronic component you may have seen which are used to reduce the current in a circuit. The code consisted of three (sometimes more) colours: the first two representing the initial two digits, followed by a third ‘multiplier’ to indicate the order of magnitude. Resistance is measured in Ohms (Ω) after the German mathematician George Ohm (rather than Marvel villain, Johnny Ohm in case you weren’t sure).

A resistor whose colour is red, green, orange, for example, would be read as 2 (for red), 5 (for green) multiplied by 10^3 (for orange) = 25 000 or 25K Ω. There’s usually another band too which indicates the ‘tolerance’ or accuracy of the first lot. And to remember it all, there’s at least one mnemonic in the style of ROYGBIV. It goes like this: Bad Bear Rots Our Young Guts But Vodka Goes Well (and then for the tolerance bit) Get Some Now. I’ll leave you to try to decode this decoder if you wish.

Tragically, the resistor colour code differed, at least in part, from my own innate synaesthetic colours and thus I was reprogrammed and forced to deny my own nature – and that of M. Cuisenaire who was surely an influence in the first place. Interestingly, I’ve only now realised that my original colour scheme seems to have returned in a kind of reawakening. I am, it would seem, the Jason Bourne of grapheme synaesthesia.

The Blind Artist

I recently read of a Turkish artist who, totally blind, paints from a kind of deeply-felt, cross-sensory perception. Eşref Armağan was blind from birth but somehow, inexplicably, can paint. And quite well as it happens, so well that he was invited by Volvo to paint one of their cars as part of a publicity campaign. It’s quite bizarre to watch him work and you’ll doubtless find yourself checking to see if he’s peeking behind those dark glasses. But, unless we’ve all been duped, Yuri Geller style, it all appears genuine and indeed we’re told from several apparently reputable sources, that he has no visual cortex at all.

Needless to say, Armağan has been subject to various studies to determine how it is he can form a mental picture of something he has never seen: how can he identify and then draw (as he does) a helicopter for example? Indeed, he’s never seen anything at all but rather he somehow ‘spacialises’ (as American psychologist John Kennedy put it) a sense of the scene he’s attempting to reproduce before putting a self-guided pencil to paper, followed by finger-painted oils in rich colours. ‘I start by imagining shapes that I have already felt’ he said in one of his interviews ‘then I form those shapes into the painting I want to create. I make a plan of the picture completely in my head before I start to draw it’. It is hard to imagine a more arresting example of our innate capacity to cross one sensory input with another, seemingly unrelated one – so exquisitely.

In his book ‘The Man who Mistook his Wife for a Hat’ Oliver Sacks presents case studies from his long career as a clinical neurologist. Among his many patients are synaesthetes who react with uncontrolled nausea when presented with certain colours, several types of savants who exceed the best urban myths, and a man (Sacks himself, as it later transpires) who wakes to find he has a tremendously heightened sense of smell after a cocaine binge. Among this menagerie of oddities, an aversion to baking paper would barely rate a mention – and I should think not. And besides, this would be an example of tactile-emotion synaesthesia as observed by scientists at Caltech. And from here it’s a short step to Roger Daltrey’s deaf, dumb and blind ‘pinball wizard’ in Ken Russell’s cult movie Tommy (based on the The Who’s album) – the poster child for olfactory synaesthetes everywhere…

Blind artists, pinball wizards and those with an aversion to baking paper may be the athletes of the synaesthetic universe but those of you with even the mildest sense of colour when imagining the days of the week are still experiencing the phenomena – even if it is as ‘also rans’. We may no longer accept the once-popular view that the blind have super-hearing (or vice-versa, so to speak) – despite the Stevie Wonders and Ray Charles of the world – but it stands to reason (and even demonstration) that our remaining senses will pick up the slack as needed. Indeed this re-routing of sensory inputs has a name: cross-modal neuroplasticity and it is, one could argue extreme-synaesthesia. But more on that another day…