|InfoVis.net>Magazine>message nº 126||Published 2003-07-14|
|También disponible en Español|
The digital magazine of InfoVis.net
Colour is normally regarded as a property of light, its wavelength. In such a definition, micro waves or FM broadcasting signals would also be colours since the only difference with light is its wavelength. Visible light goes from 380 nm to 780 nm whereas FM broadcasting is in the range of meters. In reality we only know about visible light colour, that is the only one our retina is capable of processing.
So there’s no such a thing as colour “out there”. The experience that we call colour can be relatively unrelated to the properties of light, depending on what else the brain is experiencing at the same time or even what’s it expecting to see.
We are used to the basic names of colours like red, green, blue, etc. We even speak about “greenish yellow” but that’s not so in all cultures. A study conducted by Berlin and Kay* (1969) on more than 100 languages of different cultures showed that the primary colour names are considerably consistent across cultures although different cultures have a different number of them. Although the study and its further continuations have been a matter of a certain controversy it’s worth considering it here. (See Paul Kay's personal page)
In those languages that only have two words for colours, they are always white and black. Of those that have more names for colours, the third is always red. The fourth and fifth are either green and yellow or yellow and green. The sixth is blue, the seventh is brown and only then come, grey, violet and other colours in no special order.
The important thing is that this ordering of the six primary colours coincides with the colour opponent theory of colour that establishes that, from the perceptual standpoint, there are six primary colours arranged as opponent pairs along three axes. These three axes correspond to the three channels that can be obtained combining the stimulus of red, green and blue cone cells in the retina.
There is physiological evidence0 given by deValois** in cells of the brain of primates that imply that even though the cells in the retina obey the trichromacy theory, those in the visual cortex obey the opponent colours theory. The naming of colours also abounds in this direction.
English speaking people use eight categories to refer to colour (red, blue, green, pink, purple, orange, yellow and brown). Jules Davidoff of Goldsmith’s College of London found that the Berinmo tribe of Papua New Guinea has only five names for the same range of colours. Apparently there’s not only that the Berinmo make rougher divisions but that they experience different things than English speaking people when they look at the same colour.
This could mean that having a language based concept maybe necessary in order to distinguish two colour categories. Another explanation states that since the Berinmo language has not developed concepts to make finer distinctions between colours, although their neurons are able to detect the difference, it does not reach higher cognitive levels since there isn’t a concept mapping for it that could reach the conscious level.
That colour is a variable perception can be easily seen looking at some simple visual illusions (see the enclosed figures).
There are many other examples, but the important thing is realising that perception is not a monolithic issue. Ultimately it depends on the specific person our work tries to address.
For this reason the unconscious but otherwise usual approach to interface and web design of considering that everybody perceives and even behaves in the same way [as the designer] leads to a uniformity and lack of innovation we have to avoid. An interdisciplinary approach is required in these days of homogeneity.
* Berlin, B., and Kay, P. Basic color terms: Their universality and evolution. Berkeley and Los Angeles: University of California Press, 1969.
** DeValois RL, Abramov I, Jacob GH (1966) Analysis of response patterns of LGN cells. J Opt Soc Amer 56: 966-977.
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