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Color Vision Deficiencies in Human Subjects

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Author: Crystal Beran

Grade Level: 6th - 9th; Type: Life Science

Objective:

To see if male or female humans are more likely to exhibit some form of color blindness.

The purpose of this experiment is to test human males and females to determine if one gender or the other is more likely to exhibit some level of color vision deficiency.

Research Questions:

  • How does the eye distinguish between different colors?
  • What are rods?
  • What are cones?
  • Why is red-green color vision deficiency the most common form of the disorder?
  • Why is color vision deficiency more common in males than in females?
  • What types of jobs require perfect color vision and why?

It is estimated that 8-12% of males of European origins and 0.5% of females of European origins exhibit some level of color vision deficiency. This deficiency can be manifested as a complete lack of color vision (the subject would see everything in gray scale),  a lack of red-green vision, or other variations. To test for this condition, scientist Shinobu Ishihara developed a series of colored plates. These plates show dots of various colors arranged to form images. For people with normal vision, the hidden images should be easy to find but for people who have some color vision deficiencies, certain images will be impossible to see.

Materials:

  • 30 or more human subjects (the more the better)
  • Copy of Ishihara plates

Purchasing the Ishihara plates will make this experiment quite costly. It is recommended that you visit your local library, your school’s science lab or the library of a University to borrow the plates for your tests.

Experimental Procedure:

  1. Obtain a copy of the Ishihara color plates.
  2. Find a test subject (you should alternate between male and female subjects to come out with an even number of subjects of each gender).
  3. Ask permission to test your subject for color vision deficiency.
  4. Have the subject look at each plate and tell you what the hidden image shows.
  5. Record results on a chart such as the one below.
  6. Repeat steps 2-5 on a number of subjects (the more subjects you have the more accurate your results will be).
  7. You may want to record racial information from your subjects to determine if certain races may be more prone to some form of color vision deficiency. Make sure you ask permission from your test subjects before you do this. 

Subject: (A, B, C… do not use names) Gender: (male/female) Race: (optional)

Ishihara plate
Correct
Incorrect
Plate tests for…
1
 
 
Red/green
2
 
 
General
3
 
 
Blue/yellow
4
 
 
General
5
 
 
General
6
 
 
Red/green

 

Terms/Concepts: Color blind;  Color vision deficient; Rods; Cones; Normal vision; Peripheral vision; Night vision; Color wheel; Sex-linked genes

References:

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