7 ways to cheat the ishihara thumbnail

7 Ways to Cheat the Ishihara


  1. Varikuti 2020 – Effect of EnChroma glasses on color vision screening using Ishihara and Farnsworth D-15 color vision tests
  2. Akkaya 2014 – Discrimination of Ishihara Test Plates Through a Red Filter
  3. Oli 2018 – Efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test
  4. Joshi 2015 – Use of red contact lens in dyschromatopsia
  5. Lu 2020 – Some of us see the world in a different light
  7. Hardy, Rand & Rittler 1947 – The Ishihara Test as a Means of Detecting and Analyzing Defective Color Vision
  8. Schmidt 1952 – Effect of Illumination in Testing Color Vision with Pseudo-isochromatic Plates
  9. Jurgensen 1947 – Industrial Use of the Ishihara Tests for Color Blindness
  10. Murray 1935 – The Ishihara Test for Color-Blindness: A Point in Ethics
  11. Jordinson & Minshall 1959 – Tests for Color Vision (Ishihara 1951)

The essay by Elsie Murray is a very interesting, short read.


It can suck to be colorblind, and especially to have a clump of ugly little dots laugh at you as you realize that you will never be able to… uh, drive a train. This little Ishihara plate is often what keeps us apart from dream jobs, so today on Chromaphobe, I am going to give you 7 ways to CHEAT your way past the Ishihara Test.


Before we get started… I’ve been grappling for a year with the ethics on whether I should make this video. The ethics of occupational screening against the colorblind is contentious and definitely a video in itself. Certainly, I have no qualms in helping a mildly colorblind man in China bypass an ishihara test that aims to block him from getting a personal driver’s license. On the other hand, the ishihara test IS appropriately used to prevent the colorblind from working in roles where color vision is ACTUALLY critical to the safety of them or the public.

So why am I making this video anyway…

First, there is not much more information in this video than what can be found through the first page of google results for “how to cheat the ishihara test”. I assume someone actually motivated enough to cheat is also capable of the most trivial of online research.

Second, all of these methods can be neutralized, in a way, so after going through all the ways a test taker – the SUBJECT – could cheat on the test, I’ll also explain exactly how the test givers, the INVIGILATORS: like optometrists, ophthalmologists, etc. – can not only detect, but also avoid cheating and likewise make their own testing fair and accurate.

Not to spoil the ending, but the answer is almost always… stop… using… the ishihara…


The ishihara test is made up of a number of pseudo-isochromatic plates, or PIPs. If you are interested in how PIPs work – how they detect colorblindness – I have a short video about that, which I’ll also link at the end of the video, but it’s certainly not necessary to understand this video.

The Ishihara book comes in 10, 14, 24 or 38 plate variants, though most occupational Ishihara testing uses the 10 or 14 plate versions. Regardless, the color vision of a subject can usually be confidently classified as deficient in just a few plates. Depending on the organization, 2 to 6 plates incorrectly answered results in a failure of the test. As I have protanopia, I tend to fail ALL the plates, but if I were motivated to beat the Ishihara, I definitely could. Let’s look at 7 methods to give you that edge.


Number 1 on the list is probably the first thing that came to mind… color corrective glasses. Several brands of so-called colorblind glasses are even marketed as helping you pass colorblind tests.

The most common glasses: EnChroma Lenses, aren’t actually made for helping with testing, and depending on the version of EnChromas you have, will probably not help much, though one study found that they DID improve Ishihara scores for Deutans. The goal of EnChromas is to distort color as little as possible, while knocking up the saturation, which is not what you need to cheat at the Ishihara.

For that, you need a pair of glasses that IS designed to distort colors, namely Pilestone glasses, Colormax, or really any maker of magenta- or yellow-tinted lens, either intended for the colorblind or not. In fact, I’ve got some simple colored gels here that essentially have the same effect as these glasses would have.

Here is a PIP that I have filtered so we are all seeing it as if we were colorblind. Now notice how this red gel suddenly makes an unreadable PIP readable. That’s what the glasses do… intentionally distorting color, while not actually improving color vision.

The colors of a PIP are carefully chosen to lie along a confusion line, so ANY kind of blunt-force distortion will generally make them easier to see, but a careful choice of lens color is still necessary to get the biggest effect, or one that helps with the most plates.

There are lots of different glasses that would “work” to beat the Ishihara… but while you will be allowed to wear standard prescription glasses during your test, it will be almost impossible to find a invigilator that would overlook you wearing color corrective glasses, or glasses with any visible tint whatsoever. Kinda hard to hide that…


Method number 2 is contact lenses. While an invigilator would immediately spot glasses, a contact lens would take quite a bit more attention to detail on their part. Unfortunately, there are not many options for contact lenses because none of the major color corrective lens companies yet offer contact lenses.

The most viable options are ChromaGen or X-Chrom lenses. These lenses have been around since as early as 1974 and comprise a single red-tinted contact that you wear on one of your eyes.

You may be familiar with cheap $20 red-tinted lenses; I even used them to make a vampire film in University. They specifically color the iris, but allow unfiltered light to enter the pupil, so as to be visible, but not affect color vision. The ChromaGen or X-Chrom are the opposite: filtering the light entering the pupil, therefore distorting the colors similar to colorblind glasses, but not changing the color of the iris, which would be a dead giveaway to the invigilator.

However, this trivial difference means a huge markup. Instead of $20 for two lenses, you will be paying $450 for one lens. What do you get for this price tag?

Well, one study showed a 100% efficacy of the lenses, allowing colorblind subjects to pass the ishihara with no mistakes, and another showed that colorblind subjects made half the number of errors.

However, Joshi describes the story of a subject applying for the military in India who failed the Ishihara once, then when retaking it, proceeded to pass. He was found to be wearing a red contact lens to cheat the exam and was summarily executed… not really, it was India, not Communist China.

In a related note, a 2020 report out of Jiangsu Province in China described a man who tried to cheat his way to a driver’s license by wearing such a red contact lens. After the doctor raised the alarm, the colorblind man was seized by police and to quote the report… “properly handled”. Seriously guys… be careful with contacts.


Method number 3 involves using bad lighting. The colors of a PIP are so exact, that the “color temperature” of the white light used to illuminate the book must be between 6-7000K, equivalent to bright sunlight. A light that is too warm or too cool can distort the colors, which will generally be to your advantage, making the tests easier to read. So if you can somehow arrange for the warm light of an incandescent bulb, or the cool fluorescent light of a school classroom, it may give you a small boost to your score.

One of the creators of the HRR test – a test far superior to the ishihara – even noted: “…as they are presently administered, [psuedoisochromatic plates] have become as much tests of the lighting system used as they are tests of the subject’s color discriminatory ability.”

In addition to wam or cool colored lights, using lighting with a poor CRI – or color rendering index – can also help to distort the colors, yet would not be detectable to the invigilator. Funnily enough, this may be the only instance EVER, where a low CRI is desired. LEDs and Incandescent bulbs have a high CRI, but fluorescent lights have a low CRI that can give you some extra distortion on those PIPs.

Regardless of what light source is used, the most important feature is that it’s as bright as possible, as long as it’s not making you squint. As we turn down the brightness of a light source, you can see how the colors get more difficult to differentiate. Likewise, the brighter the light source is, the more distance your eye will be able to detect between colors of confusion; meaning the PIPs will be easier to read. This part isn’t even cheating. The Ishihara guidelines state that the test must be bright enough, but does not give an upper limit to brightness, so make sure the lights are turned up BRIGHT and are positioned so there is no glare on the PIPs.


Method number 4 involves stretching the rules that the Ishihara guidelines outline for the invigilator. According to the instructions, the book must be placed exactly 75cm in front of the subject. On the contrary, I have found that some PIPs can be easier to read when observing from either closer OR farther, so you can play with this if possible.

Also, the 3 second time limit for each plate is not just due the impatience of the invigilator… getting to study a PIP for 10 seconds could help you solve a PIP, which you wouldn’t be able to see in only 3. I bring this up, because the 3 seconds is not a universally enforced limit. If you can find an invigilator that is a little looser with the rules – either from ignorance or sympathy for the colorblind – that bit of extra time can give you a tiny boost.

Actually, one paper found, that a motivated layman who read the rules of the ishihara and applied it to 100 industrial employees disagreed 30% of the time with the diagnosis determined by an Ishihara expert. Another described that the ishihara test used for the US military during WW2 let 50% of colorblind subjects pass due to the “carelessness” and “incompetence” of invigilators.

So if you can get a careless, incompetent or – okay – “sympathetic” invigilator to administer your test, your chances of passing go up a lot.


Method number 5 is all about practice. Okay, also not cheating, per se, but practicing with the precise test you will be taking can increase your chances of passing, because the Ishihara is a ‘trainable’ test… just another one of its fatal flaws.

Simply being familiar with the font of the numerals used in the Ishihara – knowing their strangely unique shapes, can give you an edge. I extracted the numerals from the ishihara plates and generated some solidified versions of them here.

First, note that there is no zero, which is already a useful piece of information.

Second, the shapes almost look like they were taken from different font families. Most have unique features, such that they can be identified while only looking at one nondescript part of the numeral. Look at where the curves are, where the flats are, where the… bulbous protrusions are – these can all give you an edge when trying to differentiate between a 5 and a 6, for example.

Even with my protanopia, one of the strongest forms of red-green colorblindness, there is one plate where I can make out just the tip of a numeral in the top left. If I was taking the Ishihara for the first time, I’d be stuck guessing between 4 numbers, but because I’ve practiced…

I know from its placement in the circle that it’s a single-digit not double-digit solution, and because of the angle, I can also guess that it is more likely to be a 7 than a 2 or 3, for example.

This “trainability” was fixed in PIPs designed after the Ishihara, namely the SPP, which uses digital numerals and the HRR, which uses shapes. But the ishihara just sticks to its nostalgic stylized fonts for no good reason.


Of course, when you practice the test so many times, you are going to start noticing patterns, and that’s why my 6th method for cheating the Ishihara test – and definitely the most controversial on this list – is Memorization. Controversial, because with just a few hours of preparation, even someone with total color blindness can completely break the Ishihara test.

In 1935, just 18 years after the first publishing of the ishihara plates, Elsie Murray – a color vision researcher – wrote a scathing open letter to American Weekly, which had re-published the Ishihara plates and their corresponding solutions:

The plates have been duplicated along with an easily memorized key… and exposed in public places, reducing the fifth edition to a parlor game… Most examiners refuse to bother to present the plates in variable order to foil cheating… the mischief done to science and to the general public by the commercial exploitation of the present edition is irreparable.

The easy solution for the publishers of the Ishihara plates would be… to randomize the numbers in each book or or at least change them every few years, but they didn’t do that. Tracking down the oldest version of the Ishihara plates that I could find, they have not changed since at least 1951. Before that, with the exception of an early switch from Hiragana characters to roman numerals and the addition of some different kinds of plates prior to 1951, I imagine they have probably never changed. The unwillingness of the former and current publishers of the Ishihara plates to change the numbers in every edition is frankly mind boggling and makes memorization soooo much easier.

As I said earlier, the Ishihara book comes in 10, 14, 24 or 38 plate versions, but each of the smaller versions is a complete subset of the larger version. That is, all of the plates of the 14 page version are also in the 24 page version, and so on. However, they are NOT in the same order, so you have to make sure you know which version you are getting before you start memorizing.

Luckily for you potential memorizers, occupational screening is USUALLY done with the 14 plate version and memorizing all of the numbers therein is almost trivially easy… equivalent to memorizing, like 2 phone numbers… which may be a terrible analogy nowadays considering some of you probably can’t even remember your own phone number… but uh, say… equivalent to remembering all 14 jersey numbers of the 1995 Chicago Bulls lineup… easy.

Despite this, the ishihara does have one defense against memorization. The ability to reorder the pages. 

You see, the Ishihara test is technically a binder, not a book. That means that the pages CAN be removed and reordered to make it harder to memorize.

However, as Elsie Murray pointed out in 1935, most invigilators do not reorder their pages. And if the several ASMR youtube videos I’ve watched of “optometrists” with deep cleavage are any indication of real optometrists, you can usually rely on the books being in the original order, for no other reason than it makes scoring easier for lazy invigilators.

So if you’re up for crossing your fingers and hoping whoever gives your test is just as lazy, then just memorizing the 14 digits in raw order… 12-8-29-5-3-etc. may work…

Even if the pages have been re-ordered though, it’s far from game over. The plate number is printed on every page, so you could just memorize the answers associated with a page number, which will help even if the plates have been reordered. The problem with this method is the font size of those plate numbers are so small that it’s unlikely you’d be able to read them without getting noticeably closer to the book, something that is explicitly forbidden in the rules.

There are a few other memorization tricks to give you a small advantage:

  1. Memorize the “Transformation” plates. These are the plates that will look like one number to a color normal, but a different one to the colorblind. For example, when you see this plate, and it appears to you as 21, you should know that the true answer is always 74. If you see 70, you already know there are no zeroes in the real solution set, and in that case, the real answer is always 29.
  2. Memorize the “Hidden Digit” plates. These plates more colloquially known as the reverse Ishihara are solvable by the colorblind, but typically NOT by color normals. For example, where you see a 73, a color normal should see nothing, so you must also claim to see nothing.
  3. Know what all the possible numbers are. In the entire set of 38 plates. If you can’t decide whether something is a 9, 8 or 0, just know that there are no plates with “9” or “0” as the solution, so choose 8.
  4. Memorize the colors of the plates… which sounds like really crap advice, I know, but even I see 5 distinct color schemes in the plates, all of which I’ve named after the most prominent color that *I* see. They definitely aren’t the real colors, just a way for me to categorize them in my head… and with that I can remember a smaller subset of solutions for each color scheme.

By themselves, these 4 techniques may help you improve your score by a plate or two, but they aren’t really a fool-proof solution. For THAT, we’ve got to kick the memorization up a notch and learn some Dot Pattern Recognition. The Ishihara plates were all originally hand painted decades ago, so the dot pattern is unique to each plate. You can therefore pretty quickly identify each plate by focusing on a shape in a specific region of the dot pattern, typically at the very top of the plate.

Personally, in these three plates for example, I see a Crab, a Clown, and Lightning each of which have become obvious to me upon seeing those plates and allow me to quickly give the correct answer within the 3 second time limit. You’ll probably find different shapes that stand out for you, but find your shapes, and start practicing…. A process that you may have guessed takes hours and hours to get right, but… time well spent if it allows you to get every plate correct. And hell, many standards allow you to miss HALF the plates and still pass the test, like for the FAA.

Is dot pattern recognition really the silver bullet for defeating the Ishihara? Allow me to switch perspective…


Dear Invigilators,

Unlike subjects using contact lenses, it can be quite hard to figure out if a subject has memorized the solutions.

As an invigilator, your first line of defence – obviously – is reorder your plates, and then reprint your solution card to match that specific order. It helps against the simple “telelphone number” style memorizers, but not those using more robust forms of memorization. During my own practice with dot pattern recognition, I’ve only come up with 2 observations that could give away my technique:

  1. The fact that every plate takes me 2-3 seconds to answer since I have to go through the complex process of finding my shape and relating it to a number. A color normal would typically answer in less than a second since they immediately see the number, but 2-3 seconds is still within the rules and could just mean a subject is slow or being careful.
  2. If I screw up a plate, my incorrect answer would likely be a correct answer for a different plate. If the plate’s answer is 73 and I say 45… a number that visually looks nothing like 73, and at the same time is the answer to a different plate… that is quite the fishy coincidence.

Those two points are the only ways I could think of for detecting dot pattern recognition and they certainly don’t constitute catching the cheater red handed… or red-pupiled in the case of tinted contact lenses. So whaddya do if you’ve got an inkling that they’re cheating?

The obvious course of action would be to give them a better, unmemorizable test like the D-15. Unfortunately, you are typically bound by some specification or mandate to use a specific test, namely the Ishihara.

While broadly sticking to the Ishihara plates, you can also try focusing on the path-tracing PIPs. In these PIPs, the subject must trace a winding path with their finger or a brush instead of recognizing a number. These were originally included to test illiterate subjects, but are also useful, in that memorizing a path is much harder than memorizing a digit.

Unfortunately, the 14 plate “concise” edition, which is usually specifically mandated by occupational standards has none of these tracing plates, which are relegated to the 38 plate “complete” edition (13).

Technically, you can’t fail a subject by using a different test not mandated by their potential employer and almost any organization that accepts multiple different color vision tests requires the subject to only pass one of them, even if they fail all the others.

In the end, you can’t unequivocally or even confidently PROVE that a subject is cheating without breaking the rules of the Ishihara test yourself.

I can imagine, it is super frustrating, but it will always be a problem as long as we keep using the Ishihara. As an invigilator or someone designing an occupational standard, your best option to foil the cheaters is simple. Use a different test.

The ability to be memorized is a fatal flaw of the Ishihara test, one which other less-common tests like the D15, FALANT or City University Test fundamentally avoid, and as such, they are much harder to cheat.

If everyone who uses the ishihara instead used a much less cheatable pseudoisochromatic plate, like the HRR, which has existed since the 1940’s – everyone: the invigilators, the public… even the colorblind ourselves… would be better off.

Sincerely, Protan


And yes you heard that right, ditching the Ishihara benefits the colorblind. It’s not very intuitive, I know… how are we better off by not using the one test that we have the backdoor key to… the ONE test we could – hypothetically – cheat on.

While it’s clear the ishihara benefits the dishonest colorblind subjects, let’s not forget it also punishes the honest colorblind subjects.

The Ishihara is intended as a screening test, and is therefore much stricter than other tests.

The idea is, if you pass the Ishihara, your color vision is definitely okay for anything. if you fail the Ishihara, it simply means further testing is required.

The nasty truth is though, many subjects and invigilators kinda treat the Ishihara as the end of the line and subjects are usually not informed upon failing it that they have other really decent options for passing a different, approved test.

The FAA has a dozen different tests that someone can take instead of the ishihara. Pass any one of them and you’re good. Most people will opt to take the Ishihara because it’s the one test that their local optometrist has on hand, but it’s also one of – if not the hardest test to pass of the lot.

The Farnsworth Lantern is generally the test of choice for a pilot’s license from the FAA, and there are countless internet testimonials of people who miserably failed the Ishihara, but were able to pass the FALANT perfectly. And under each of these stories, there are always comments from colorblind guys who had failed the ishihara and immediately, prematurely gave up on their dreams.

So how do we best beat the Ishihara? We kill it… there… that’s the 7th method… kill the ishihara…. But its never going to die unless organizations concerned about color vision start to see the ishihara as a problem. Cheating is happening already… you can google it. We just need to draw attention to it. Get organizations scared of cheating and they will stop mandating the ishihara.


Okay… maybe you think I’ve crossed the line with this video. Maybe you think I am encouraging colorblind people to cheat their way into a job that they are not capable of safely performing and putting themselves and others at risk… but that’s not my intent, AND I don’t think that will be the outcome.

I made this video for the same reason that the lockpickinglawyer routinely demonstrates how easy Masterlock locks are to pick… not to encourage theft, but to show how irresponsible it is to trust Masterlock for your security.

Highlighting the weaknesses of the Ishihara is the best way to get people to STOP USING IT.

88 years ago, Elsie Murray saw that the damage was done to the integrity of the Ishihara as soon as it was published publicly for the first time. Since then, despite much better alternatives popping up, there have been no concerted attempts to either improve the Ishihara test or to replace it.

If you really think that the risk of colorblind subjects circumventing the test is so high, if a company really wanted to neutralize that risk… then they wouldn’t be specifying that potential hires be screened with arguably the WORST colorblind test.

It’s no surprise that the organizations that do not think very hard about WHY they are excluding the colorblind, or even whether they NEED to exclude us instead of making some trivial accommodations in their processes, are ALSO the type of organizations that would just default to specifying the Ishihara to screen their potential recruits.

And maybe – from an ethical / discrimination point of view – maybe those organizations deserve to have the colorblind cheating the test.


Anyway, have any of you had any luck with using any of these methods? If you have successfully – or unsuccessfully – cheated at the ishihara, I would love to hear about it. You can leave a comment here or contact me directly through my website, chromaphobe.com.

Want to know how Ishihara Plates are designed, and how they work? Then check out this video next. This is chromaphobe.






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