No two people can inhabit the same world. Beliefs, opinions and prejudices distort reality the way mass warps the path of light. Circumstance can mean that, though we might agree that chair is red; it’s green to someone with a specific form of colour blindness. They may concede that an absence or dysfunction of long wavelength cones in the eye causes deuteranopia; but ultimately to them, the chair is green.
I’m no philosopher and I’m certainly no scientist. I simply cannot escape the significance of an analogy like this. The chair is green in the subjective. It is only red by consensus. Let’s find an alternate dimension where deutans are in the majority – now what are you sitting on?
Colour Blind Awareness states that, globally, 1 in 12 men and 1 in 200 women live with some form of this condition. 8% of my gender live their lives with dissonant chroma. My cousin ranks amongst them, as did my maternal grandfather. That we’re not inundated with stories of cars piling through traffic lights because of misread signals is deeply encouraging. A mutation which could dramatically impact upon the day-to-day of a great many people has become well managed and almost completely anonymous.
In 2005 researchers from the University of Cambridge and the University of Newcastle upon Tyne used multidimensional scaling (MDS) to explore ‘the colour dimension that is private to the deuteranomalous observer.’ The study emphasised an important correlation between “colour normal” and deuteranomalous observers – that they are both formally trichromatic (requiring three primary lights to ‘match all possible spectral power distributions.’) Despite the differences in colour perception, there is no inherent deficit or dysfunction:
MDS studies of anomalous trichromats have, however, always had a phenotypic bias: stimuli have been selected to be discriminable for the normal observer and the anomalous space has typically been found to be contracted compared to the normal. Such results reinforce the categorization of anomalous trichromats as ‘color deficient’, but this represents the viewpoint of the majority phenotype.
Interestingly the study refers to a potential evolutionary advantage gifted to anomalous/alternative trichromats. Research suggests that the efficacy of camouflage is threatened by ATs, particularly when it resembles natural foliage or terrain. Food sources and predators may become easier to clock; practical applications expressed in some primate species. Genetic drift may have allowed such individuals to make an advantageous contribution to our earliest, socialised ancestors. Hunter/gatherer parties including, though not wholly comprising ATs may have been ahead of the curve.
As expressions of the worth and wonder of re-thinking how we determine what is and isn’t a disability – as well as opening eyes to the potential benefits of any “anomaly” – discussions of colour blindness offer a delightful elegance and simplicity. Clearly, on the spectrum of what we consider disabilities, disorders, diseases…et cetera, not all animals are going to be equal. Issues will never be (ahem) black and white.
All I would say is consider the alternatives whenever you consider or encounter anyone with anomalous expressions or characteristics. Maybe you’ll find yourself ahead of the curve too.