Ishihara test — is it 24 plates or 38? Margin for error?

[jlac4]

Hey, I was hoping somebody could let me know how the Ishihara colour vision test is conducted. Will it be 24 or 38 plates? Could it even be 14? I've heard the examiner may also only ask about 6. Also, what's the margin for error? Any info you have (based on RECENT experience) would be great. Thanks x

 

[Highlandspring]

Whenever I’ve done it the nurse/doctor has given up after about 6 or 7 when it was clear there wasn’t a problem. I daresay if you struggle with the more marginal plates then they’ll carry on to try and catch out a definite issue...

 

[Marton]

Ishihara plates aren’t actually a test, but a screening technique to allow the majority to pass through, but require some to be formally tested.

Previously the Holmes Lantern was The testing methods used for seafarers, I presume the railways had a similar scheme.

Now the CAD system (or an equivalent) should apply. https://www.city.ac.uk/news/2017/ma...in-visually-demanding-professions,-says-study Gives more s
Detail on this. Seafarers usually have to pay for this themselves as part of career entry for relevant jobs, suck as deck officers.

Personally I would argue that any thing less than formal testing could be construed as discriminatory.

 

[Highlandspring]

I think you’d struggle to argue that colour vision deficiency is a disability/protected characteristic under the terms of the Equality Act 2010 and in any case employers have a statutory exemption under Schedule 9 if they can demonstrate:

1) A person (A) does not contravene a provision mentioned in sub-paragraph (2) by applying in relation to work a requirement to have a particular protected characteristic, if A shows that, having regard to the nature or context of the work—

(a) it is an occupational requirement,

(b) the application of the requirement is a proportionate means of achieving a legitimate aim, and

(c) the person to whom A applies the requirement does not meet it (or A has reasonable grounds for not being satisfied that the person meets it).

The ‘context of the work’ and ‘occupational requirement’ in the case of the railway is the being able to determine the difference between different colours under a variety of ambient lighting conditions to a very high degree of accuracy. The requirement to be able to identify colours in this way prevents accidents, which is a legitimate aim. The Ishihara test gives the railway reasonable grounds to be satisfied whether or not someone is able to meet this requirement.

 

[Sinistah]

In my medical they asked at least 14. They just went through a book and you read out the numbers you could see if any. The didn’t go overboard if it was clear there were no issues

 

[Marton]

I think you’d struggle to argue that colour vision deficiency is a disability/protected characteristic under the terms of the Equality Act 2010 and in any case employers have a statutory exemption under Schedule 9 if they can demonstrate:



The ‘context of the work’ and ‘occupational requirement’ in the case of the railway is the being able to determine the difference between different colours under a variety of ambient lighting conditions to a very high degree of accuracy. The requirement to be able to identify colours in this way prevents accidents, which is a legitimate aim. The Ishihara test gives the railway reasonable grounds to be satisfied whether or not someone is able to meet this requirement.

But it’s not an accurate test. To rely on it is not reasonable. The requirement is to see lights. Ishihara doesn’t test that which is why the MCA don’t rely on it for seafarers.

To rely on it would not be applying a correct measure so could be improper.

Of course to fail a correct test would be a reasonable ground for non employment in a safety critical role.

 

[Highlandspring]

It’s a relatively coarse test but nonetheless effective in weeding out those with even slight colour perception problems. Ishihara is simply used as a tool for sifting applicants, a bit like asking whether or not you have a driving licence or live withing xx miles of a depot. The rail industry doesn’t need to move to anything more refined while it has hundreds of applicants for every safety critical vacancy. It’s not just ‘lights’ which need to be accurately perceived by the way...

 

[ES21]

Hey, I was hoping somebody could let me know how the Ishihara colour vision test is conducted. Will it be 24 or 38 plates? Could it even be 14? I've heard the examiner may also only ask about 6. Also, what's the margin for error? Any info you have (based on RECENT experience) would be great. Thanks x

Ishihara involves a test plate that all can see, a number of plates that can be read incorrectly with red-green deficiency or not at all with total deficiency, a number that cannot be seen with defective colour vision, and a number that can only be read with red-green deficiency. So it's not how many plates you cover but how you respond to them.

In a 24 plate test, the first 15 cover the above. The next 2 are diagnostic, and the rest are for those unable to read numbers. They may shorten the test by only showing you 1 or 2 from each section - it is possible to determine normal colour vision from 6 plates. How many you are shown will likely depend on the tester and your responses. However, females tend to be carriers than actually colour vision deficient - about 0.5% of females are actually deficient.

 

[jlac4]

Thanks for your input everyone!

 

[tiptoptaff]

But it’s not an accurate test. To rely on it is not reasonable. The requirement is to see lights. Ishihara doesn’t test that which is why the MCA don’t rely on it for seafarers.

To rely on it would not be applying a correct measure so could be improper.

Of course to fail a correct test would be a reasonable ground for non employment in a safety critical role.

The Ishihara was the standard for my ENG1

 

[Marton]

The Ishihara was the standard for my ENG1

Because you passed it.

If you failed it you would be offered the opportunity for a formal test.

 

[Elecman]

My last once 6 weeks ago stopped after 8 plates, I actually asked about a previous test where I couldn’t see any number and was told there was such a plate as a check .

 

[Saracen_83]

Had this 2 weeks ago, went through about 6-7 different pages so 12-14 plates making sure I could see the numbers, as well as a “check page” which had no clearly visible numbers

 

[Elecman]

Had this 2 weeks ago, went through about 6-7 different pages so 12-14 plates making sure I could see the numbers, as well as a “check page” which had no clearly visible numbers

Where was your test carried out, just wondering if it was the same medical person who did mine as on previous tests and my last one i was never shown the “check” plate