The eyes and color
Asyia El-Kurdi Hadia Abbasi
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*We did NOT do an experimental project but we do have a method*
In this presentation, we are going to talk about how humans and animals see colors. Also what steps the eyes go through to let us see these bright colors and which colors we can see and some unusual colors we cannot see. We will also be giving examples on the way so you can understand our topic. In the end, we will be doing a little experiment with our families to see how great their color vision is. In conclusion, we will try to mention as much as we know about the eyes and color!
Why we chose this topic:
We chose this topic because we thought it would be very interesting and cool to learn about how humans, people with color blindness, and animals see and what unique colors they see that humans can't see. Because there are some colors out there that even the human eyes can't reach, and we thought it would be very interesting to research and learn about how the eyes of humans, colorblind humans, and animals see the rainbow and more. Also, most humans see color every second of their lives and don't even think about how the eyes functions to see such beautiful and bright colors. We want to show people how the eye is programmed to see color and what complicated steps it takes for us to see color. We want to inform people of how the eyes of humans (including colorblind people), and animals work to see the rainbow.
Human color vision
How the human eye functions to see color:
The main part of the eye that forms color is the retina. The retina is a thin layer of tissue that lines the back of the eye on the inside. The purpose of the retina is to receive light that the iris has allowed into the eyes, turn it into signals, and then send them to the brain which tells you which colors you are seeing. But before that step, there is the Iris which controls the amount of light entering your eyes, and the lens which lets your eyes focus on the light. In the retina, there are millions of cone cells that differentiate light into shades of colors, they function best in the light and that's why humans can't see well in the dark.
Example: How bananas appear yellow:
Most humans see bananas as yellow, and we will use them as an example for this explanation. Our eyes have cones that help us to see color, we have red, blue, green, and many more cones.
In order to see colors like yellow, the red and green cones have to work together. Seeing yellow is what happens when both the green and red cones are highly excited near their peak sensitivity, ...Hence why bananas appear to our eyes as yellow.
What color does the human eye see best?
There indeed is an answer to that and it is the color green. That is because the color green lies in the center of the spectrum, however, that's not always the case for people who are colorblind, the green that they do see is either very bright or very muted depending on the type of colorblindness they have. Yellow is also another color we can see very well because of its brightness, and it's a color that is first noticed by our eyes because it is very bright and eye-catching.
What is the hardest color to see?
Out of all colors, the color blue is the hardest to see, that's because more light energy is required for a full response from the blue-violet cones compared to green and yellow. The eye finds it difficult to focus on blue, green, and red at the same time, and focusing on blue-violet is especially the hardest. This results in a haze caused by the blue-violet spectrum, which often leads to headaches. The blue-violet light can be taken out by wearing sunglasses with yellow lenses.
Different types of color blindness:
This spectrum shows many types of color blindness and how people with these types of colorblindness see colors. Now as you can see 92% percent of humans see normal colors, while there is a very rare and small amount of people who see colors differently. People who have Deuteranomaly, Protanomaly, Protanopia, and Deuteranopia, see colors like red, green, and pink as very muted. People who have Tritanopia and Tritanomaly, don't really see colors like yellow or green. The rarest type of colorblindness is Achromatopsia, which means that they see no color.
How does color blindness occur?
Color Blindness is usually genetic, meaning it has been passed down from family. Color Blindness occurs when the sensitive cells in the retina fail to respond to light that enables people to see color. Photoreceptors are the rods and cones in the retina that help us see color. The human eye has 100 million rods, they are more sensitive to light and they are incapable of perceiving color. Cones on the other hand are responsible for perceiving color, and humans have 6-7 million cones in the retina.
Is there a solution/cure?
Color blindness is a most of the time genetic condition so there isn't really any cure for it yet, but color blindness caused by eye or brain trauma, injury, or illness can improve. If you are color blind and you want to see color effectively, you can buy special glasses called EnChroma glasses or contact lenses to help. They aren't that affordable for some, but not quite expensive as-well. Most people who are color blind are able to adjust and don't have problems with everyday activities.
Animal color vision
How does an animal's eye function to see color?
The process is almost the same as humans. Some animals have very good color sight and some very bad. It's just that different animal species have different amounts of color cone cells. Some have a lot of red cone cells, some have a lot of blues and that's the color they are best at recognizing. Some animals don't have cone cells of certain colors so they are not able to see that color. There's only one animal that is entirely color blind which is a Skate, it is a type of fish that doesn't have any color cones so can only see black and white.
The mantis shrimp:
A Mantis shrimp is a very unique creature that can see way more colors than an average human. Mantis shrimps have 12-16 types of color-sensitive cells called photoreceptors, which are 4 times more than a human, humans only have 3 photoreceptors. Mantis shrimps don’t see colors like us humans but they can detect another type of light invisible to humans called polarization. Polarization is the ability to detect a movement of light, only a few animals can detect polarization.
Does a red cape really trigger a Bull?
The answer is no. In fact, Bulls are almost fully color blind, they can only see the colors yellow, green, blue, and violet (and of course black and white). They only charge at the red fabric because it's moving, not because it is red. It's the same with all other cattle but it's just that bulls are more aggressive. The reason the matador uses a red cape is to hide his sword behind it so that when the bull charges he can stab the bull. It's all just to fool the bull and try to kill it.
How do scientists know what colors animals see?
Although there's no way to truly know what colors animals actually see, scientists can examine the cones inside the eyes and estimate what colors an animal sees. One of the techniques used to determine the color vision of fish is “microspectrophotometry.” Scientists also test for color vision with behavioral tests. In the picture, a mouse has decided that the third colored panel looks different from the others and receives a drop of soy milk as a reward.
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Thank you to my partner for this project @firstname.lastname@example.org. You have helped me a lot to get through this project. We both shared our work and divided it evenly. Without your help, our project wouldn't have gone this far. I am glad I made the decision to work with you. You are very understanding and quick. Thanks again!!!