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How We See:
The First Steps of Human Vision

Activity #1: How our environment affects color vision

Color vision is a major part of our lives that we often take for granted. We see colors around us every day, but it is not often that we take a chance to analyze our perception of colors. It is known, and can easily be demonstrated, that the colors that we see are affected by factors such as the distance from which they are viewed, the background of the object we are looking at and the lighting of the surrounding environment. In this laboratory we examine our ability to see colors when viewed under conditions. This lab will evaluate how a group of students view different colors as presented on different background colors and under different lighting conditions.


Construction paper of several different colors
2 or 3 pieces of different colored cardboard (approximately 12" by 18")
Room where lighting can be varied (lights on and off, shades or open closed, etc.)
Chart to record the results


1. Students should work in pairs or larger groups.

2. Cut one 4" by 4" square out of each of six different color pieces of construction paper.

3. Tape the squares on one of the large pieces of cardboard (for example use blue and red).

4. Make a data sheet for each participant. See the example below.

5. Set up the cardboard posters so that they are across the room (approximately 30 feet) from the student being tested.

6. Have each student look at the colored squares on the poster board and record the color they see for each of the four different conditions.

  • Dark room/ Blue background
  • Dark room/ Red background
  • Light room/ Blue background
  • Light room/ Red background

7. When each student has filled out their report form, answer the questions below. These can either be done separately or discussed as a group.

Example Reporting Form:

Name _______________

Blue /Dark Blue/Light Red/Dark Red/Light
Color #1 
Color #2 
Color #3 
Color #4 
Color #5 
Color #6 

Questions regarding data collected

Did any student see all of the colors correctly under all of the conditions?

Which colors were difficult to see on the blue background? Which colors were difficult to see on the red background?

What difference did the lighting conditions make?

Questions for consideration

How do road sign designers use this type of information when designing signs?

Based on your data from this experiment, using these colors to work with how would your design a sign for the highway to be seen at night?

Do you think this kind of color analysis is used by advertising companies when deciding how to design advertisements to sell products?

How would the results change if different types of materials were used instead of paper? For example different fabrics, plastics, etc.

What other industries do you think need to consider color schemes when designing their products?

Activity #2: Measure your ability to see

You or many people that you know wear glasses. Have you ever stopped to wonder why they wear glasses? Do they wear them all the time or only during certain activities? Do you know what "perfect vision" is? Do you know if you have 20/20 vision? What is 20/20 vision anyway?

No doubt you have already had your eyes tested several times throughout your lifetime. This is usually done in some schools on a yearly basis, and at regular medical check-ups throughout life. Optometrists have developed a standard test to evaluate your ability to see at a distance. A Snellen Chart is used. This is a chart with a series of letters in lines. The size of the letters decreases as you look down the chart. Next to the letters on the right side of the chart is a series of numbers: 200, 120, 80, 60, 50, 40, 30, and 20. In this laboratory we will test our eyesight to determine how good our distance vision is.


Snellen Eye Chart (try to borrow this from your school nurse) Notebook or paper to record your results Cardboard to cover one eye


1. Stand 20 feet from the chart (make sure there is good light in the room).

2. Cover your left eye

3. Try to read the letters in the bottom row with your right eye.

4. If you cannot read most of them (about 8 out of 10) then try the line above it.

5. Continue to move up the chart until you find a line in which you can read most of the letters.

6. Record the number at the right of the line that you can read for that eye.

7. Cover your right eye and repeat steps 3-6.

Interpreting the Results:

Since each eye is tested separately you may have a different result for each eye. They need not be the same. If you were able to read all (or most) of the letters in the last line, labeled 20, with each of your eyes then you have "normal" or 20/20 vision. That means you, like most people can see this line at a distance of 20 feet.

If the smallest letters that you can clearly see are in the fifth line then you have 20/50 vision. This means that you have to be 20 feet from the chart to see the letters that most people can see when they are standing 50 feet from the chart. If you can only see the top line clearly, then you have 20/200 vision. This means that you must be 20 feet from the chart to see what most people can see at 200 feet.

Note: This exercise is not meant to accurately measure students' vision, and is not a substitute for professional vision analysis.

Questions for consideration:

1. What is the result for each of your eyes? Are they the same? What do these numbers mean. (Write a paragraph in response to these questions)

2. If you wear glasses: Is the result different with and without your glasses? Why is this?

3. If the result for a person is different for each of their eyes what does this mean with regard to the design of their glasses?

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