Some minor concerns regarding the Ishihara Color Test

The Ishihara Color Test is a color perception test administered for the purpose of diagnosing red-green color deficiencies in patients.  Essentially, it consists of a set of colored plates, each of which contains a circle of variously colored dots – the dots differ in size and color.  Somewhere within the dots is some form of a figure – typically a number; this is usually visible to those with normal color vision and difficult or impossible to see for those with red-green defects. The reverse is true with some other plates.  In addition, there are four different kinds of plates: those on which individuals with a defect will see different things than will individuals with normal vision (transformation), those that may only be recognized by normal color vision individuals (vanishing), those that only individuals with defects can view (hidden digit), and those intended to distinguish between protanopia and deuteranopia (diagnostic).

If one “incorrectly” recognizes a certain number of the first fifteen plates (four, by Australian standards), then one is termed to have a color vision defect. However, I’ve begun thinking that this could be problematic for young children, who in some cases may be slightly hazy where numbers are concerned. Others have considered this, too – according to studies conducted in Sydney in 2005, it appears that about 75.8% of children with normal color vision make significant errors on some plates. This could be a fundamental flaw of the test.

How could the Ishihara Color Test be modified to reduce the risk of numerical confusion errors?  It seems quite possible to me that young children might, say, mistake a “1” for a “7” if both numbers are given with serifs.  Perhaps a sans serif “1” would be of help, but then, the effectiveness of plates like Ishihara 9 is based on “4” becoming “1”; this can only be accomplished with serifs.  Perhaps including a component of the test that involves reproducing the figure on paper instead of identifying it verbally could circumvent the problems caused by younger children’s poorer communication skills.

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2 Responses to Some minor concerns regarding the Ishihara Color Test

  1. Yazzy says:

    Strange that you would post about this as I had a detailed conversation about this very topic with my dad (an ophthalmologist) recently. There are alternatives to this test for children and for illiterate adults as well. Similar to the vision chart which uses shapes pointing in different directions rather than letters or numbers, there are tests which evaluate the patient’s ability to detect color without the need for him/her to be educated, accommodating children as well as adults from all walks of life. I’m not sure if this added anything to your knowledge, but an attempt has been made.

    • Sophia says:

      Thanks so much for contributing information about alternatives! I am aware that they exist, and that they are in use, but this particular post was prompted by an ophthalmologist friend that recently encouraged an intern of his to find the plates least likely to confuse visitors; I was surprised that the Ishihara is still used in some places without such alternatives’ being offered to young children.

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