The following children, who are color deficient, illustrate
how the condition can cause problems at school.
1. John is working in his reading workbook. The directions to one
item say to draw a line to the red ball. The other ball is brown. Both
colors look alike to John, so he guesses. The teacher reminds him not to
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. Peter is sitting so that the glare diminishes the figure-ground
contrast. The teacher wonders why he is copying from a neighbor's paper.
3. Tommy ordinarily seems to enjoy reading aloud. Today, however, he
doesn't volunteer and balks when the teacher calls on him to read. The poem
in the reader is printed in blue on a purple background.
4. Susan, a bright and articulate youngster, 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.
5. T.J. was very out going in pre-school & kindergarten. He loved
to wave his arms and volunteer to answer questions the teacher asked. The
only time he did not volunteer answers was when it came to learning or
identifying his colors. A lot of the colors looked the same to him. They
just had different names.
6. The kindergarten teacher notices the kids during art class teasing
Jimmy. The other kids think it is funny that Jimmy's stick people have
7. The kids at school told the teacher Jeff was cheating during kick
ball. They said he would break the rules by kicking the ball when it
was out of bounds. They accusingly stated the boundary lines on the green
grass were clearly marked with orange chalk. Jeff, rather than admitting
he could not see the boundary line, simply quit playing with the other
kids during recess.
This series of plates is designed to provide a test which gives a quick and accurate assessment of colour vision deficiency of congenital origin. This is the commonest form of colour vision disturbances.
Most cases of congenital colour vision deficiency are characterized by a red-green deficiency which may be of two types: first, a protan type which may be absolute (protanopia) or partial (protanomalia), and secondly a deutan type which may be absolute (deutanopia), or partial (deuteranomalia).
In protanopia, blue-green colour appears as grey. In deuteranopia, green appears as grey. Consequently, one of the peculiarities of of red-green deficiencies is that blue and yellow colours appear to be remarkably clear compared with red and green colours. This is the basis of the Ishihara plate series.
There is also a very rare group of persons who suffer from total colour blindness and show a complete failure to discriminate any colour variations, usually with an associated impairment of central vision with photophobia and nystagmus. For more on this see the personal account of vision scientist and achromat Knut Nordby.
An assessment of the readings of plates 1 to 21 determines the normality or defectiveness of colour vision. If 17 or more plates are read normally, the colour vision is regarded as normal. If only 13 or less than 13 plates are read normal, the colour vision is regared as deficient.
It is rare to find a person whose recording of normal answers is between 14 - 16 plates. Such a result requires the use of other colour vision tests.