May is one of my favourite months of the year! With the warming weather, the colour pallet of the earth changes from neutral hues of browns and beiges to bright greens and gem tone colours as flowers start to blossom and bloom! But have you ever wondered how we see colour or if we all see colour the same? Because colour is such an important part of our environment and daily living, we decided to write a blog article on understanding how our eyes see colour!
What Is Colour?
To fully understand what colour is and how we see it, we must first understand exactly what colour is! Colour is a product of light. When light hits an object, some of the light rays reflect off the object, and some light rays are absorbed (black). The speed (wavelength) at which the light is reflected back to the eye results in a colour. different light wavelengths = different colours.
Most people may think that black is a colour. However, science does not! This is because we see black because of the absence of colour!
How Do Our Eyes See Colour?
The inside portion of our eyes called the retina is responsible for our colour vision. The retinal has a light-sensitive layer which helps us to interpret light and colour. This layer is made up of 2 types of photosensors called rods and cones. Rods are not colour sensitive but are sensitive to the amount of light. They are concentrated in the peripheral part of the retina and help us see objects in low light conditions. Cones are mostly found in the centre of the retina, a part called the fovea. Cones respond to red, green, and blue light. Different colour wavelength stimulates the cones in varying amounts. This information is then passed from the cones to the visual cortex of the brain along the optic nerve. The brain then processes the information which then tells us what colour we’re seeing.
Most of us have 6 to 7 million cones within our eyes. Almost all cones are concentrated in the fovea which is a 0.3 millimeter spot on the retina!
The following Youtube Video by Brown Science Center is a good visual aid to understand colour:
Check out this visual demonstration by Brown Scient Center on Youtube:
Why Don’t We All See Colour The Same?
When the cones within the eye don’t function properly it results in conditions such as colour blindness or colour deficiency (CVD). People who are colour blind or have a colour deficiency are not able to see the colours red, blue, and green to the same intensity of a person with normal colour vision.
It is a myth that people who are colour blind see no colour at all.
Because colour is such an important part of our environment, it is important to have colour vision checked at an early age. Part of a child’s eye exam is evaluating colour vision.