by Melanie Lilliston
Stephend F. Austin State University, Spring 2000
Return to Perception, Spring 2000frontpage.
In a world of many technological advances, color perception hasbecome a very important issue. One of the main advances pertains tocolor technology. An increased emphasis on color technology hasraised awareness of the issue of color blindness. Many people are notaware of the origins of color blindness and the different types,although many people are affected by it. One in two hundred femaleshave this defect while in males the defect occurs in one and twelve (Lewis, Reitzammer & Amos, 1990). That is about two percent of thefemale and eight percent of male populations (Sewell, 1983). It isimportant to look at the prevalence of colorblindness in children andidentify the problems associated with it.
Color deficiencies can take many forms but are generally groupedtogether and known as colorblindness. The different types of colorblindness 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 lessclear until it is perceived as gray at 492 nm (Goldstein, 1999).Deuteranopia causes a person to perceive blue at short wavelengthsand see yellow at long wavelengths with a neutral point at 498 nm.The most rare form of color blindness is tritanopia. Theseindividuals perceive blue at short wavelengths and perceive red atlong wavelengths with a neutral point at 570 nm (Goldstein, 1999).Protanopia and deuteranopia are commonly referred to as red-greenblindness. These forms of colorblindness are sex linked; the generesponsible is on the X-chromosome, with the dominant gene passed bythe mother. With the female (XX), the anomalous locus on one Xchromosome has a prevalence of 8%, and is most often paired with anormal dominant lens on the other X chromosome. This can lead to aprevalence of color deficiencies in females of about 0.64%. In themales (XY), the anomalous locus for color vision is also on the Xchromosome, which has no counterpart on the Y chromosome. This leadsto an increased number of color deficiencies in males, about 8%(Adams & Haegerstorm-Portnoy, 1987). Thus, females are lesslikely to be colorblind due to the fact that they have twoX-chromosomes, if one chromosome is a carrier of color blindness thenthe 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 drugsalter the sensitivity to specific lengths of light, often causingcolor deficiencies. There are also several contraceptives that havebeen linked to color deficiencies (Knowlton & Woo, 1989). Doctorshave become more aware in the past couple of years and are trying toeducate mothers-to-be on the importance of maintaining a healthy dietduring pregnancy. By monitoring the drugs to which a mother exposesher unborn child, the less likely the child will have a colordeficiency.
Many areas of concern are present when dealing with colordeficiencies in children. One of the main problems associated withcolor deficiencies is that it is very hard to detect. Many timeschildren simply adapt to the environment and are not tested to see ifthey are color-deficient. They get by with adapting to the situation,and may never realize they suffer from colorblindness. They maycreate their own shortcuts to maintain their problem as a secret.Since the child has been exposed to the deficiencies for his or herentire life it is commonplace and an everyday occurrence to them.They are not aware of their disability and many times do not notifytheir teacher of this potential problem. Also, many teachers are notaware of the issue of color blindness and may label the childlearning deficient as a result. Dr. Barbara Lewis, Dr. AnnReitzammer, and Dr. John Amos (1990) explain a situation that can beavoided once colorblindness is detected. "Tom" is typically an happyreader, but today he does not volunteer to read. His problem stemsfrom the fact that the story is printed in blue with a purplebackground. "Tom" is unable to see the letters clearly and therefore,is unable to read with confidence. If a teacher is not educated inthe area of colorblindness he or she may misdiagnose the problem, butif they are made aware of the possibility of color deficiencies,special measures can be taken to help students. Allowing "Tom" toread off of black and white copies of the story will help improve thecontrast and allow him to read with confidence.
Since the effects of color blindness can be quite harmful, it isnecessary to learn more about its effects on learning as well asteaching. Many teachers are not aware of the effects of colordeficiencies in young children. If teachers were made aware of thepotential problems of colorblindness, steps could be taken to aid thestudents with these deficiencies. It is often taken for granted thatall children see in color. Books are printed in a variety of colorsand with colorful graphics making them very appealing to the normalcolor-perceiving person. These publishing techniques make itdifficult for the color-deficient student to see the material and tolearn. Color is also incorporated with flannel boards, colored maps,transparencies, books with colored print, colored counting beads, andgreen or brown chalkboards (Sewell, 1983). There is no way a childwho is unable to see the material will be able to process and learnit.
Problems with contrast can contribute to the learning issues ofthe visually-disabled student. A child may not actually display allthe characteristics of colorblindness but may not be able todistinguish certain colors apart such as gray and black. Thisidentification problem can also slow down the learning process. Manyteachers have modified their teaching in order to accommodate thecolor deficient child. These modifications are really smallconsidering the lasting effects they will have on the child's future.Some of these modifications include labeling with words or symbolswhen the child needs color recognition, increasing the contrast byusing white chalk on a black board, being aware of "trouble" areas,and by making black and white copies of colored text. By simplyincorporating these techniques, a teacher can radically alter achild's performance in academics (Lewis, et al 1990). The sooner thecolor deficiency can be identified the sooner accommodation can bemade to help the child.
Testing of color blindness can take place as early as the age ofthree, and is recommended to parents before the age of seven. Statelaw does not require colorblindness testing, leaving theresponsibility with the parents. Most of the tests consist ofpsuedoisochramatic displays (different colored dots) with shapeshidden in them (Waggoner, 2000 ). Several new techniques have beenintroduced in the past few years. One of the most popular tests wasinvented by Dr. Terrance Waggoner whose own son was diagnosed ascolorblind at age 6. This test contains fourteen plates with simpleobjects such as circles, stars and squares; and pictures such asboats, balloons and dogs. Small children are able to recognize theseobjects with ease. This test is quick and easy for all ages and iscalled 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, theVelhagen-Pfugertrident, the Matsubara, and the Ishihara test. TheVerriest Test, created in 1981, requires children to match plateslike dominos. With the Fletcher-Hamblin test, children are tested ontheir ability to match a given color to those in a drawing. ThePease-Allen Test contains four plates, and is used for detecting bothred-green and blue defects (Pease & Allen, 1988). The Optokinetictest is a mechanical test that detects the absence of color by movingpainted cylinders and monitoring the eye's movements. TheVelhagen-Pfugertrident test uses the letter "E". Children are askedto turn the plate and match it to the presented orientation. Avariation of this test is the Ohkums, which uses a letter "C" in thesame manner. In the Matsubara test pictograms are used and the childmust name them. The final test is the Ishihara test that is used forchildren aged four to six. There are eight plates in which childrenare asked to recognize common figures. No matter what test is used,it is imperative that a child is tested and has their records markedfor future reference.
If the problem is not detected by the time they are adults,students may inappropriately choose a career that requires colorvision. 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 astudent may choose a career, train for the career, and go to work inthe field before they realize that a color deficiency has preventedthem from performing his or her job effectively. A good example ofthis is a medical student who went through training and was notadmitted into medical school because he could not identify skin,blood, or tissue color. Another example of color affecting a person'sperformance in a specific field is a policeman. In one officer'sinstance his first case was dismissed because he wrongly identifiedthe color of the get-away car. These two simple examples demonstratejust how important it is to identify if a person's performancesuffers from a color deficiency. If a child is not identified ascolor deficient, their career decisions may result in many hours offrustration and it could damage their self-esteem while trying tochoose a career.
Much information is known about colorblindness but its effects onchildren's learning is a topic that still needs exploration. It is anissue that cannot be totally fixed but one that can be controlledwith the right resources.
Adams, J.A. & Haegerstorm-Portnoy, G. (1987). Colordeficiency. Diagnosis and management in vision care (pp.971-713).Boston:Butterowrths.
Cotter, S.A., Lee, D., & French, A. (1999). Evaluation of anew color vision test: "Color Vision Made Easy". American Academy ofOptometry, 76, 467-475.
Gaines, Rosslyn. (1972). Variables in color perception of youngchildren. Journal of Experimental Child Psychology, 14, 196-218.
Goldstein, B. E. (1999). Sensation & Perception, FifthEdition. Pacific Grove, CA: Brooks Cole Publishing.
Knowlton, M., & Woo, I. (1989). Functional color visiondeficits 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 visiondefects: what teachers should know. Reading Improvement, 27, 31-33.
Pease, P.L. & Allen J. (1988). A new test for color screeningcolor vision: concurrent validity and utility. American Journal ofOptometry 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 VisionTest for Three to Six Year Old Pre-School Children. [Online],Available.http://members.aol.com/nocolorvsn/color5.htm