Essay --

Colour vision refers to the ability of an organism to distinguish between stimuli based on the wavelengths of light they emit, reflect or transmit. We live in a world filled with colours which we use as an advantage on a day-to-day basis; to signify danger, make things stand out and to help us categorise the world around us. However, 1 in 12 males and 1 in 200 females (approximately 4.5% of the population) suffer from some sort of colour vision deficiency or blindness (Colour Blind Awareness, 2014). It is therefore of interest to investigate what is different about the visual system in this minority and why the occurs. This essay will investigate this by considering what ‘colours’ actually are in terms of wavelengths of light, investigating the differences of what we perceive to be a ‘coloured’ world based on the different visual systems of non-human animals. Finally it will look at what makes the system of colour blind humans different, questioning whether we can really consider them colour blind at all. The basis of our vision is a direct cause of photons (light) entering our eyes from the environment around us. We examine these photons in one of two ways; either the intensity of the light (number of photons) or by examining the wave energy. This wave energy is what enables colour vision, and refers to our eyes ability to detect slight changes across the electromagnetic system of light. As a whole this consists of a variety of parts; cosmic rays, gamma rays, x-rays, ultra-violet light, visible/white light, infrared, microwaves and radio waves. Our human eyes are only sensitive to the visible white-light which ranges from approximately 400 to 700 nanometres (nm) across the electromagnetic system. Newton is heavily credited towa... ...t differences in colour therefore relies on the sensitivity of different types of cone cell within our retina. This is what enables us to see the full spectrum of visible light from blues into the deep reds. It is evident from studies with dogs, birds, snakes and other animals that having a different number of cones, or having these cones sensitive to different wavelengths causes a completely different perspective of our colour world. As a result Dichromatic or Monochromatic humans who are missing a certain type of cone(s), or even trichromatic humans with a cone sensitive to an anomalous wavelength can be labelled as colour blind. Whilst these ‘colour blind’ individuals are usually still able to detect differences in colour across the visible spectrum of light they ultimately see the colour world in an abnormal way to an individual with a normal visual system.