Colours III: Function, Purpose, & Effect of Colour

This is part III in my ongoing series about colour. Read also part I, Colours I : The Nature of Colour 1 , and part II, Colours II : The Nature of Colour 2.

Sight is the dominant human sense. Of the perceptional [from our five ordinary senses of perception] information our brain receives, 80-90% is related to sight, and of that more than 80% is related to colour. So colour is important to us; in terms of perception it totally dominates our brain. Not mainly as an aesthetic quality, obviously that is secondary, but it must have a purpose for our survival.

The most obvious presence of colour in our lives is related to food. Visually it creates contrasts in nature, so we can find our food easier if we clearly perceive the difference between, for instance, red and green; and it makes it easier for us to distinguish one foodstuff from another. Since many of the plants growing in nature are poisonous, such recognition can be a matter of life and death.

The colour pigments of plants are almost always biochemically very active compounds, essential for the function of nature. Green chlorophyll or carotenoids are very good examples. When those compounds has a meaning in human life, they are either beneficial for health, or they are toxic. In both cases they have medical significance.

But why would plants, without any visual sense themselves, produce these strong visual effects? From the beginning, one might suspect that colour is just a side-effect of chemical structure, but along with the parallel development of animals, a complex interaction between them and plants evolved. In order to get help with reproduction, to spread their seeds, some plants wanted to make certain animals eat them; others wanted to scare animals away by looking toxic or being similar to a toxic plant. Colours then evolved as a communication system between plants and animals, and such colours are sometimes specifically adapted to the sight of a certain class. Flowers and insects are a good example of this sort of adaption and communication.

I might add that the aroma of many species of flowers and fruit, another way of communication in nature, is a result of breakdown of carotenoids, that is, from pigments.

The colours of animals serve different purposes, such as camouflage, communication, or chemical adaptation to the environment. The latter is a means to utilise the biochemical advantage of a certain pigment, most notably melanin.

Colours of minerals, at least appear as a mere side-effect of their structure and composition, but with no direct visual function of their own. After all, it is hard to imagine that iron oxide is reddish or an emerald is green for a visual purpose.

In human culture, colours have evolved as a major system of communication. Their symbolic meanings are mainly dependent on culture, but they sometimes transcend cultural differences in a way that seems to have to do with human nature itself.

Colours affect our minds and trigger certain emotions. They can make us happy or sad, bored or interested, attracted or repelled, excited or calm, active or passive, even strong or weak; they can even activate or suppress appetite and hunger. To some extent they can be used for purely medical purposes; and they can be used for other forms of manipulation. Green hospital walls are there to make us calm; a specific shade of pink makes us weak, measurable in reduced muscle strength; black and red can be used to instil fear and a sense of threat; mould green or rotting-meat purple can cause nausea, especially in combination with food; red makes you active, hungry, perhaps aggressive. A skilled use of colours can generate the emotions and reactions the manipulator desires. This is no exact science, however. Even if, on the average, all people react similarly to similar colours, there are differences between cultures and individuals. The personal experience of an individual can alter his reactions to colours completely. If he has been close to dying while lying in bed starring at a sky-blue wall; sky-blue can very well be a colour triggering fear and pain forever, for that specific individual. So, reactions to colour are intimately intertwined with our individual memory and depend on how strong and traumatic experiences have been associated with certain colours in our own past.

Names of colours are sometimes confusing, because it might not always be obvious what they refer to, especially if the perspective is historical. Purple is a good example. It has been used to describe different shades, varying from blue and violet to red-brown-greyish. What they did really mean with “purple” during a certain age, we will never really know. Cinnabar and vermilion have been used for different shades of red to red-orange, and azure can be almost any blue. But the most peculiar is green. In East Asia many languages cannot, or until recently could not, make a distinction between blue and green; and in old Persian green, black, and dark are confused. Women are sometimes poetically described as green which then means dark [example: sabz-malih, a green beauty]!

Copyright © 2010, 2021 Meleonymica/Mictorrani. All Rights Reserved.

(Lead image by Antonio López/Pixabay, CC0/Public Domain. The image has been cropped and digitally altered.)

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