by Melanie Lilliston
Stephend F. Austin State University, Spring 2000
Return to Perception, Spring 2000 frontpage.
In a world of many technological advances, color perception has become a very important issue. One of the main advances pertains to color technology. An increased emphasis on color technology has raised awareness of the issue of color blindness. Many people are not aware of the origins of color blindness and the different types, although many people are affected by it. One in two hundred females have this defect while in males the defect occurs in one and twelve ( Lewis, Reitzammer & Amos, 1990). That is about two percent of the female and eight percent of male populations (Sewell, 1983). It is important to look at the prevalence of colorblindness in children and identify the problems associated with it.
Color deficiencies can take many forms but are generally grouped together and known as colorblindness. The different types of color blindness include protanopia, deuteranopia, and tritanopia. Individuals with protanopia perceive short-wavelength light as blue, and when the wavelength is increased, the blue becomes less and less clear until it is perceived as gray at 492 nm (Goldstein, 1999). Deuteranopia causes a person to perceive blue at short wavelengths and see yellow at long wavelengths with a neutral point at 498 nm. The most rare form of color blindness is tritanopia. These individuals perceive blue at short wavelengths and perceive red at long wavelengths with a neutral point at 570 nm (Goldstein, 1999). Protanopia and deuteranopia are commonly referred to as red-green blindness. These forms of colorblindness are sex linked; the gene responsible is on the X-chromosome, with the dominant gene passed by the mother. With the female (XX), the anomalous locus on one X chromosome has a prevalence of 8%, and is most often paired with a normal dominant lens on the other X chromosome. This can lead to a prevalence of color deficiencies in females of about 0.64%. In the males (XY), the anomalous locus for color vision is also on the X chromosome, which has no counterpart on the Y chromosome. This leads to an increased number of color deficiencies in males, about 8% (Adams & Haegerstorm-Portnoy, 1987). Thus, females are less likely to be colorblind due to the fact that they have two X-chromosomes, if one chromosome is a carrier of color blindness then the other can compensate and not allow the recessive gene to surface.
Many factors contribute to color deficiencies besides genetics. Some specific drugs such as caffeine, alcohol, tobacco, marijuana, and cocaine can also alter the genetic makeup of a child. These drugs alter the sensitivity to specific lengths of light, often causing color deficiencies. There are also several contraceptives that have been linked to color deficiencies (Knowlton & Woo, 1989). Doctors have become more aware in the past couple of years and are trying to educate mothers-to-be on the importance of maintaining a healthy diet during pregnancy. By monitoring the drugs to which a mother exposes her unborn child, the less likely the child will have a color deficiency.
Many areas of concern are present when dealing with color deficiencies in children. One of the main problems associated with color deficiencies is that it is very hard to detect. Many times children simply adapt to the environment and are not tested to see if they are color-deficient. They get by with adapting to the situation, and may never realize they suffer from colorblindness. They may create their own shortcuts to maintain their problem as a secret. Since the child has been exposed to the deficiencies for his or her entire life it is commonplace and an everyday occurrence to them. They are not aware of their disability and many times do not notify their teacher of this potential problem. Also, many teachers are not aware of the issue of color blindness and may label the child learning deficient as a result. Dr. Barbara Lewis, Dr. Ann Reitzammer, and Dr. John Amos (1990) explain a situation that can be avoided once colorblindness is detected. "Tom" is typically an happy reader, but today he does not volunteer to read. His problem stems from the fact that the story is printed in blue with a purple background. "Tom" is unable to see the letters clearly and therefore, is unable to read with confidence. If a teacher is not educated in the area of colorblindness he or she may misdiagnose the problem, but if they are made aware of the possibility of color deficiencies, special measures can be taken to help students. Allowing "Tom" to read off of black and white copies of the story will help improve the contrast and allow him to read with confidence.
Since the effects of color blindness can be quite harmful, it is necessary to learn more about its effects on learning as well as teaching. Many teachers are not aware of the effects of color deficiencies in young children. If teachers were made aware of the potential problems of colorblindness, steps could be taken to aid the students with these deficiencies. It is often taken for granted that all children see in color. Books are printed in a variety of colors and with colorful graphics making them very appealing to the normal color-perceiving person. These publishing techniques make it difficult for the color-deficient student to see the material and to learn. Color is also incorporated with flannel boards, colored maps, transparencies, books with colored print, colored counting beads, and green or brown chalkboards (Sewell, 1983). There is no way a child who is unable to see the material will be able to process and learn it.
Problems with contrast can contribute to the learning issues of the visually-disabled student. A child may not actually display all the characteristics of colorblindness but may not be able to distinguish certain colors apart such as gray and black. This identification problem can also slow down the learning process. Many teachers have modified their teaching in order to accommodate the color deficient child. These modifications are really small considering the lasting effects they will have on the child's future. Some of these modifications include labeling with words or symbols when the child needs color recognition, increasing the contrast by using white chalk on a black board, being aware of "trouble" areas, and by making black and white copies of colored text. By simply incorporating these techniques, a teacher can radically alter a child's performance in academics (Lewis, et al 1990). The sooner the color deficiency can be identified the sooner accommodation can be made to help the child.
Testing of color blindness can take place as early as the age of three, and is recommended to parents before the age of seven. State law does not require colorblindness testing, leaving the responsibility with the parents. Most of the tests consist of psuedoisochramatic displays (different colored dots) with shapes hidden in them (Waggoner, 2000 ). Several new techniques have been introduced in the past few years. One of the most popular tests was invented by Dr. Terrance Waggoner whose own son was diagnosed as colorblind at age 6. This test contains fourteen plates with simple objects such as circles, stars and squares; and pictures such as boats, balloons and dogs. Small children are able to recognize these objects with ease. This test is quick and easy for all ages and is called the "Color Vision Test Made Easy" (Cotter, Lee, & French, 1999). Several other tests that are well known include the Verriest , the Fletcher-Hamblin, the Pease and Allen, the Optokinetic, the Velhagen-Pfugertrident, the Matsubara, and the Ishihara test. The Verriest Test, created in 1981, requires children to match plates like dominos. With the Fletcher-Hamblin test, children are tested on their ability to match a given color to those in a drawing. The Pease-Allen Test contains four plates, and is used for detecting both red-green and blue defects (Pease & Allen, 1988). The Optokinetic test is a mechanical test that detects the absence of color by moving painted cylinders and monitoring the eye's movements. The Velhagen-Pfugertrident test uses the letter "E". Children are asked to turn the plate and match it to the presented orientation. A variation of this test is the Ohkums, which uses a letter "C" in the same manner. In the Matsubara test pictograms are used and the child must name them. The final test is the Ishihara test that is used for children aged four to six. There are eight plates in which children are asked to recognize common figures. No matter what test is used, it is imperative that a child is tested and has their records marked for future reference.
If the problem is not detected by the time they are adults, students may inappropriately choose a career that requires color vision. Some of these careers include police, fire protection, electronics, military service, pilot training, medical training, fashion designer, cosmetology, biology, agriculture, decoration, chemistry, as well as many others (Sewell, 1983). In some cases a student may choose a career, train for the career, and go to work in the field before they realize that a color deficiency has prevented them from performing his or her job effectively. A good example of this is a medical student who went through training and was not admitted into medical school because he could not identify skin, blood, or tissue color. Another example of color affecting a person's performance in a specific field is a policeman. In one officer's instance his first case was dismissed because he wrongly identified the color of the get-away car. These two simple examples demonstrate just how important it is to identify if a person's performance suffers from a color deficiency. If a child is not identified as color deficient, their career decisions may result in many hours of frustration and it could damage their self-esteem while trying to choose a career.
Much information is known about colorblindness but its effects on children's learning is a topic that still needs exploration. It is an issue that cannot be totally fixed but one that can be controlled with the right resources.
References
Adams, J.A. & Haegerstorm-Portnoy, G. (1987). Color deficiency. Diagnosis and management in vision care (pp.971-713). Boston:Butterowrths.
Cotter, S.A., Lee, D., & French, A. (1999). Evaluation of a new color vision test: "Color Vision Made Easy". American Academy of Optometry, 76, 467-475.
Gaines, Rosslyn. (1972). Variables in color perception of young children. Journal of Experimental Child Psychology, 14, 196-218.
Goldstein, B. E. (1999). Sensation & Perception, Fifth Edition. Pacific Grove, CA: Brooks Cole Publishing.
Knowlton, M., & Woo, I. (1989). Functional color vision deficits and performance of children on an educational task. Education of the Visually Handicapped, 20, 56-62.
Lewis, B.A., Reitzammer, A., & Amos, J.F. (1990). color vision defects: what teachers should know. Reading Improvement, 27, 31-33.
Pease, P.L. & Allen J. (1988). A new test for color screening color vision: concurrent validity and utility. American Journal of Optometry and Physiological optics, 65, 729-738.
Sewell, J.H. (1983). Color counts too! Academic Therapy, 81, 329-37.
Waggoner, T. L. (2000, February 6). New pediatric Color Vision Test for Three to Six Year Old Pre-School Children. [Online], Available. http://members.aol.com/nocolorvsn/color5.htm