Traffic lights were originally invented by J.P. Knight, William Potts, and Garrett Morgan (even before the invention of automobiles) to help ease traffic jams on roads.
Traffic lights are signaling devices used for controlling traffic at road junctions, roundabouts, and pedestrian crossings.
They are automatically operated and contain colored lights that are typically red, amber/yellow, and green.
The green light signifies “go” (moving traffic), the yellow signifies “ready or proceed with caution”, and the red signifies “stop”.
These traffic lights contain light waves, which are part of the electromagnetic spectrum.
The electromagnetic spectrum is made of 7 types of waves including radio waves, X-rays, infrared, microwaves, gamma rays, ultraviolet light (UV), and light waves (visible light).
Light waves are just like radio waves and the only difference is the length of the waves.
Table of Contents
- How the Eye Perceives Color
- What is Color Blindness?
- Types of Color Blindness
- How Severe Can Color Blindness Be?
- How Do Color Blind People See Traffic Lights?
- Are There Any Restrictions for the Color Blind?
How the Eye Perceives Color
Light travels through the eye into the retina, which is located at the back of the eye.
The retina contains numerous cells that are classified as rods and cones.
Rods have the responsibility of relaying the different levels of light while cones have the responsibility of differentiating between colors.
Both of them, however, have the function of transferring/transporting the light received by the retina through the optic nerves into the brain.
The brain has a kind of depot for receiving everything that comes into it; this depot is known as the thalamus.
The thalamus receives (the light) information and sends it to the appropriate part of the brain.
In the case of the eyes, the part that the thalamus sorts the received information into is known as the visual cortex.
The visual cortex is located at the back of the brain and is responsible for producing and decoding the image that your eye sees.
After it does this, it transports it to the prefrontal cortex, which is located around your forehead and above your eyes. It is then that your eyes can recognize/perceive whatever color is visible to you.
Therefore, we see different colors according to the way our cone cells process and differentiate these colors.
Because of these differences, some of us experience what is known as color blindness.
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What is Color Blindness?
Color blindness, also known as color vision deficiency, is a condition that causes a minimal ability to distinguish between certain colors.
It is often an inherited condition but mostly caused by diabetes, certain eye diseases and medications, and multiple sclerosis (MS).
It is more common in men than in women. You can discover if you’re color blind by taking the Ishihara test.
This test is carried out using 32 colorful cards that contain various circles, each with a different hue, brightness, and saturation.
Color blindness is also usually self-diagnosable and you immediately know when you start having symptoms like the inability to distinguish between shades of red and green.
It is noteworthy to mention that color blindness doesn’t have a cure yet, but can be managed.
Types of Color Blindness
There are three types.
Complete Color Blindness
It is also known as monochromacy or achromatopsia.
This situation means your rods and cones have a defect and are unable to function properly or aren’t even present at all.
In this case, you’re most likely unable to see colors and are close to being blind to any type of color except black and white.
This type of color blindness is the rarest form an individual can have.
Red-Green Color Blindness
It is sub-divided into 3 categories.
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A situation whereby the green color will have more of a red shade. This is the most common of this type of color blindness.
This depicts a case where the red color has more of a green shade and will be less bright. It is the opposite of deuteranomaly.
Protanopia and Deuteranopia
Are situations where you will be unable to tell which color is green or red. In other words, no ability to differentiate both.
Blue-Yellow Color Blindness
This is sub-divided into 2 categories.
A situation whereby it is hard to tell the difference between “blue and green” and “red and yellow”.
A situation in which you cannot even tell the difference between the combinations of different colors.
For instance, you won’t be able to tell the difference between purple and red, blue and green, yellow and pink. All colors will look dull to you.
How Severe Can Color Blindness Be?
As said earlier, there are rare cases of color blindness disability known as achromatopsia. In this situation, the individual can only see all colors like black and white.
Because there is no cure for this condition, the individual living with achromatopsia can live a colorful life with color blind glasses or EnChroma glasses.
As for the other two cases (red-green and blue-yellow color blindness), it can fluctuate between a mild and severe state.
An individual may have only slight difficulty in telling the difference between various shades of colors. And another may have grave difficulty in differentiating between the hues and saturation of various shades of colors.
For example, if an individual has a severe case of color blindness, they would have difficulty in telling which color is red and which is green because they see red as green and green as red.
In this kind of situation, how can such an individual tell when the traffic light is giving the command to stop or to go?
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How Do Color Blind People See Traffic Lights?
Colorblind people can see traffic lights using the following methods/tricks.
The first trick to decipher traffic light commands is to have at the back of your mind that the red light is always on top, the yellow in the middle, and the green below.
Since all three lights cannot be on at once, it will be easy to tell which command is giving the light because you have the arrangement registered in your mind.
Another trick is to use EnChroma lenses, which will make colors visible and vibrant.
Whenever you’re going out or driving, always have someone else with you who isn’t color blind.
Are There Any Restrictions for the Color Blind?
In most developing countries (like Brazil), there is a prohibition to drive against color-blind individuals.
Whereas in developed countries (like most parts of Europe), the first letters corresponding to the traffic light colors are used as indicators.
Also, graphics describing the commands are located near each light.