Colour blindness
Colour blindness is usually a condition present since birth. Male children are much more likely to have this disease. Colour blindness can also be a result of some diseases involving the optic nerve and the retina. It may also be caused by some medicines.

Examples of school difficulties because of color vision deficiency
  1. Sometimes workbooks have directions that require the student to draw a line to the red ball. The other ball is brown. Both colors look alike to the colour blind student, so he guesses. The teacherfinds that he is correct sometimes and when wrong reminds him not to be careless.
  2. A teacher is writing vocabulary words on a green chalk board with yellow chalk in mid-afternoon. There is a glare on the board from unshaded windows. The colour blind student is sitting so that the glare diminishes the figure-ground contrast. The teacher wonders why she is copying from a neighbour's paper.
  3. A student who ordinarily seems to enjoy reading aloud. Today, however, he doesn't volunteer and baulks when the teacher calls on him to read. The poem in the reader is printed in blue on a purple background.
  4. A normally bright and articulate student was asked to go to the front of the class and read from the blue green book on the teachers' desk. She went to the front of the class and just stood there looking at the pile of different colored books. Not knowing which one to pickup, she started to cry.
Many of the colour blind use contrast to be able to read, when the contrast is low their blindness may be unmasked. Also, colourblindness is rarely absolute, i.e. the colourblind usually see colours but they are washed out. In situations where the colour-on-colour contrast is low their dysfunction is unmasked.

Colour Vision | Introduction to colour blindness | More on colour blindness
Disclaimer  | Privacy policy  | Cookie policy
©   Dr. Bhaskar Ray Chaudhuri 2020