On Monday night, like all dutiful Science Communication students in the making, I tuned in to the first episode of this season of Horizon on BBC2. It was the first science programme I’d watched in a while – certainly since my final year physics exams finished sometime back in June.
It was due to be an interesting episode on the nature of colour perception and interpretation, revolving around the central theme of: ‘Do You See What I See?’ In other words, as the programme took some pains to clarify, do I see the colour Red, say, in the same way that someone else sees the colour Blue?
Now this is a question with quite some pedigree, having made the rounds at dinner parties since long before the science of colour was properly understood. Or, indeed, since dinner parties really took off.
The Ancient Greeks
The first dinner guest I can find talking on this issue is Democritus, the ancient Greek philosopher who is also celebrated as the father of atomism. Between mouthfuls of dolmades and pita bread in tzatziki dip, he apparently found the time to say that: “all the perceptible qualities […] are relative to us who perceive them, and in nature there is nothing black or white or yellow or red.” This, at least, is how Galen of Pergamon remembers the conversation, and even though these two academics are separated by over five hundred years, I see no reason to doubt the man unequivocally declared to be the greatest surgeon of his day. It’s not as though medical students have any difficulties remembering conversations they’ve had over a glass or two of ouzo.
Now while the Ancient Greeks can in fairness be said to have come up with all the good ideas first simply because they came up with all the bad ideas first as well, there is a fascinating twist to the tale of this particular conclusion. Namely, there has been scholarly debate over the past hundred and fifty years as to whether the Hellenes perceived different colours in a different way from us.
Bizarrely enough, this idea seems to have received its first airing from the Victorian Prime Minister William Ewart Gladstone, a name familiar to pub quizzers up and down the country. Known in his day as something of a Greek scholar, he observed that the poet Homer had ascribed colours to everyday objects considered odd even by the standards of Victorian interior design.
Within the pages of the Iliad and the Odyssey, for instance, the sea was famously described as ‘wine-dark’ while the sky would frequently be the colour of bronze. Now, a lot of foolish conclusions have been reached from this meagre amount of data and it is not my intention to add my own plastic bottle to the rubbish-heap of conjecture. Having searched around, however, it does seem that one of the most convincing explanations is that the language of Homeric Greece divided the colour wheel in a different way from what we would be familiar with in modern English.
The Himba Tribe
The reason I make this obscure historical digression will hopefully already be clear to any of you who happened to watch Monday’s episode. To those of you have who not been able to (whether because of location-specific iPlayer restrictions or lack of time), I should point out that a substantial portion of the episode revolved around the Himba tribe of Northern Namibia.
The Himba people today number over 20,000, a minor miracle in its own way given that they were among the west African tribes to suffer under the stiletto heel of Imperial Germany. Lothar von Trotha, the German governor of South-West Africa at the turn of the last century, is perhaps the figure most frequently associated with the acts of genocide, murder and extreme brutality carried out in the name of his home country. It gives me a dark ironic satisfaction to note that one of von Trotha’s predecessors in his role as Reichskommissar was Ernst Göring, an indication that the rubbish doesn’t fall far from the ancestral bin.
The Himba tribe were revealed to have divided the colour wheel very differently from we Western Europeans, distinguishing only five colour groups where we (apparently) see eleven. This led to an amusing piece of footage where a succession of African tribesmen and women were faultlessly able to spot the difference between two shades of green which to my eyes were totally indistinguishable. Later on in the programme, a rogue light blue square masquerading in a circle of placid green counterparts passed entirely (and unbelievably) unnoticed.
The reason for this striking difference in colour perception appears, on the face of it, to be similar to the case of Ancient Greece. If a tribe groups together shades of blue, red and green under a collective name, much as we might exclusively group together different shades of green, then it is possible that confusion will arise when it comes to pointing out any particular swatch in an identification parade of its neighbours. It is naturally difficult for us to imagine such a reshuffling of mental labels, but we can get our heads round the idea that the files are still in the office, even if a replacement secretary has placed them in a different filing cabinet.
What surprised me about this whole episode was the way in which it dealt with the old chestnut of what is pompously known as ‘linguistic relativity’ and even more pompously known as the ‘Sapir-Whorf hypothesis’. What this field of philology-cum-anthropology-cum-neuroscience dealt with was the extent to which language could influence thought and thereby perception as well as emotion.
One of the many shaky pillars of this academic edifice was Benjamin Whorf’s claim that the Inuit people have a vast array of words to describe the phenomenon of frozen, crystalline precipitation – viz, snow. A similar meme has more recently been injected into our culture’s bloodstream by the television show QI, which cited the number of words used in Albania to refer to the phenomenon of upper-lip hair growth – viz, moustaches.
What this latter example helpfully illustrates about the former is that very often one word can be used in Albanian (such as, according to the internet, the word fshes), which can easily be replaced by a string of words in English (long broom-like drooping moustache with bristly hairs. Apparently). The English sentence achieves the same goal as the Albanian word, and so clearly tells us nothing about the way the Albanian mind works.
So is a different issue at stake with the Himba? Almost certainly. The issue in question was very tellingly skewered by a segment analysing the brains of babies who had not yet acquired the use of language, and comparing the areas of increased activity with children old enough to speak. When the older children were exposed to flashes of coloured light, high levels of brain activity were recorded in areas key to the forming and processing of language. Needless to say, these areas were not activated in their younger siblings.
This is hardly a surprising conclusion to those of us familiar with the following optical/mental illusion:
Try and read the following lines of text, pronouncing aloud the colour in which the word is printed – not the word itself.
BLACK YELLOW BLUE BLACK RED GREEN BLACK
ORANGE GREEN RED YELLOW BROWN BLUE BLACK
Assuming that I have not missed something here and have a) printed the illusion correctly and b) experienced the same sensation as all of you, then this task shouldn’t be as easy as it first appears. There is clearly a heavy linguistic element involved in the recognition of colours – in fact, one could even say that the colours are not visually recognised so much as they are verbally labelled.
All of which means that when members of the Himba tribe were confronted with the swatches of colour, they had to perform a “similarity judgement” based on their individual experiences. I put the phrase “similarity judgement” in “quotation marks” because this elegant phrase was used by one of the academics involved with this experiment to describe what was going on in the minds of his subjects.
Which inexorably seems to lead on to yet another subject: the deep (often orthogonal) parallels that exist between the senses of hearing and sight. Clearly, all we can be expected to do with regards to colour identification is a ‘similarity judgement’ based on another colour whose name we have been taught. If so, what is the difference between this and the musician who is able to identify a C based on the number of tones separating it from an A# which has just been played?
In other words, is our perception of sound as much of an illusion as our perception of colour? Of the huge range of wavelengths of light which falls on our eyes, our brain chooses a very specific sub-range to interpret as colour. Likewise, of the huge number of vibrations of different wavelengths which pass through the air, our brain picks out a certain range which can be interpreted as noise. The range of sights and sounds increases and decreases with age, sex and even with species. Where both these senses are concerned, our brain proves itself to be a tool whose sole specification is to maximise our ability to navigate the Earth’s surface.
There is so much more to be said here – from the evolutionary nature of colour perception to the comparative complexity of our eyes and ears. These are fascinating subjects, and I am indisputably the wrong person to speak about any of these issues with authority.
The one thing I can recommend with confidence is that you bring this subject up at the next dinner party you get invited to. Who knows what great sages might not be leering suggestively at you over the non-alcoholic punch.