How Do We See Colour?

Have you ever wondered how we actually see colour? Do we all interpret colours in the same way?  These are very interesting questions and so we decided why not dedicate this week’s blog post to understanding how we see colour. I hope you enjoy it and check out some of the cool links! Enjoy…

We see reflected light as colour.

In order to understand how we see colour, we must first explore what colour is. Check out Crayola’s great explanation of what colour is on their website:

Colour is the aspect of things that is caused by differing qualities of light being reflected or emitted by them.

To see colour, you have to have light. When light shines on an object some colours bounce off the object and others are absorbed by it. Our eyes only see the colours that are bounced off or reflected.

The sun’s rays contain all the colours of the rainbow mixed together. This mixture is known as white light. When white light strikes a white crayon or marker barrel, it appears white to us because it absorbs no colour and reflects all colour equally. A black crayon or marker cap absorbs all colours equally and reflects none, so it looks black to us. While artists consider black a colour, scientists do not because black is the absence of all colour.

Pretty cool, eh! So in essence what we are seeing or interpreting as colour is really just reflected light. Everything being absorbed or not being reflected is not seen as colour. And this is dependant on the object’s properties.

How Does The Eye Understand Reflected Light As Colour

The part of the eye responsible for this amazing process is called the retina. The retina has light sensitive photoreceptors, which help interpret light. There are two types of photosensors: rods and cones. Rods are located mostly at the edge of the retina and are responsible for helping see in dim light settings. These photosensors are not sensitive to colour and help interpret white and black information to the brain. Whereas cones function to see colour in bright light and are found mainly in the center of the retina. Cones are sensitive to red, green, and blue light.

Check out this visual demonstration by Brown Scient Center on Youtube:

We Don’t All See Colours In The Same Way?

According to the Colour Blindness Awareness Organization “Colour (color) blindness (colour vision deficiency, or CVD) affects approximately 1 in 12 men (8%) and 1 in 200 women in the world.” People who are colour blind are unable to see reds, blues, and greens fully. So contrary to popular belief a person who is colour blind does not always see no colour. Additionally, someone who is unable to see the full range of colour may not even know they are colour blind. This is one instance where one person may interpret light differently than another person. Other individuals termed as tetrachromats have a fourth photoreceptor making them even more light sensitive.

There are still other circumstances where two individuals seeing the same object interpret different colours. Scientists are uncovering some interesting data on how we interpret light waves. Even though two people are seeing the same wave length they may still interpret the object to be a different colour than the other. Why? New research suggests this can be due to things like mood and experiences.

So it seems that colour is more subjective than objective. Do you know if you can see all the colours? Set up an appointment with one of our Doctors of Optometry professionals and get a comprehensive eye assessment.

Did you know your family eye doctor has special tools and techniques to assess whether you are colour blind? Give us a call or book online with Dr. Sharma.

We love helping our patients see their very best!

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