Vision

My friend and I were arguing about what nearsightedness and farsightedness was. She said when a person is nearsighted, they have trouble seeing close objects and farsightedness was when you have trouble seeing far away. I argued the opposite. We made a bet and whoever is wrong owes the other person $10. In order to prove that I'm right, I had to do some research.

The visual process goes a little something like this:

The eyes receive light energy and then transform that energy into neural messages that the brain then processes into what you see. Light rays reflected from an object pass through the cornea which protects the outer layer of the eye and bends light to provide focus. The rays also go through the pupil and lens. Depending on the thickness of your lens, your vision has a better focus on the objects that are close or far away. Once the light waves pass through the cornea, pupil, and lens, they strike the bottom of the retina. The image of the object is upside down in the fovea and then the retina processes neural impulses that are sent to the brain and it perceives an upright image.

Color:

When we see color, we really see electromagnetic energy. The spectrum ranges from gamma rays who have short wavelengths to radio waves who have long wavelengths. Humans can see only part of the electromagnetic spectrum: Visible light.






When we see light, the hue, intensity, and saturation influence what we see. Below is a clarification of what they are.

Hue: The dimension of color that is determined by the wavelength of light

• We perceive the color blue as blue and yellow as yellow

Intensity: The amount of energy in a light or sound wave as determined by the wave's amplitude.

Brightness and loudness

Saturation: The ratio of the dominant wavelength to other wavelengths in the color.

•  How pure the color appears to be.

The aspects of our color vision:



Photoreceptors-

Cones: Receptor cells that are concentrated near the center of the retina.

• Function in daylight and well-lit conditions.
• Can see fine details

Rods: Retinal receptors that detect black, white, and gray.

• Is necessary for peripheral vision.
• Will function when cones don't.

What your cones see What your rods see

 

 

 

 

 

What is the opponent process theory?

The theory stating that our color vision is measured by opponent colors. We cannot see opponent colors together, though.

The opponent colors are:

Red and green
Blue and yellow
Black and white

A great example of this theory is this picture:

If you stare at the red dot for 1 minute, and then stare at a white wall or paper, you see the opponent colors. Because you have stared at the image for so long, your neural responses get tired so you see the opponent colors.


So finally, what is nearsightedness and farsightedness?


Nearsightedness: A condition in which close objects appear clear & sharp, and far objects appear blurry.

Farsightedness: A condition in which close objects appear blurry, and far objects appear clear & sharp.

Looks like I was right! :)