How to Pass the Farnsworth D-15 Color Vision Test

Search results for "how to pass the Farnsworth D-15" are full of articles promising specific tricks, color-correcting contact lenses, and "proven strategies." Most of it is either marketing for tinted lenses (which you can't wear during the test anyway) or hopeful thinking presented as advice.

Here is the truth: whether you pass the D-15 is overwhelmingly determined by your underlying color vision. If you have normal color vision, you will pass without preparing. If you have a moderate or severe deficiency, no preparation will let you pass. If you have a mild deficiency — deuteranomaly is the most common — the test is exactly where preparation can matter. Mild defects are right at the edge of what the D-15 is designed to catch, and the conditions of the test can push your result one way or the other.

Everything in this guide is about controlling the conditions and avoiding mistakes that drag borderline candidates into a fail. None of it is a workaround for actual color blindness.

The Farnsworth D-15 is a 15-cap arrangement test. You place 15 colored caps in chromatic order, starting from a fixed reference. Caps that someone with normal color vision arranges in the natural color-wheel sequence get confused by people with color vision deficiency in characteristic ways: protans confuse reds with greens and browns, deutans confuse different reds and greens, and tritans confuse blues and yellows.

The test scores two things: total error magnitude (how far off your sequence is from correct) and the direction of your errors on the color wheel (which tells the examiner the type of deficiency). The pass criterion in most occupational settings is phrased as "no major crossings" — meaning no errors where you swapped two caps from opposite sides of the color circle. Minor adjacent swaps (placing 5 before 4) are normal and don't count against you.

Knowing what the test is looking for is itself half the preparation. Many borderline candidates fail not because of their color vision but because they rushed, second-guessed themselves into bigger errors, or didn't understand that adjacent swaps are fine.

The day-of and week-of factors that genuinely affect your performance:

Sleep and eye fatigue

Sleep-deprived eyes have reduced contrast sensitivity and slower color adaptation. This is a real, measurable effect — not a wellness platitude. If you're testing first thing in the morning, get 7+ hours the night before. If you're testing in the afternoon, avoid 4+ hours of screen time immediately before; your color discrimination drops measurably after extended near-work.

Hydration and dry eyes

Dry eyes scatter light and reduce the saturation of perceived colors. If you wear contacts, this is amplified. Use preservative-free artificial tears the morning of the test if your eyes are typically dry. Avoid heavy alcohol the night before — it's strongly dehydrating.

Glasses, contacts, and tinted lenses

Clear prescription glasses and contacts are fine — wear them exactly as you normally would. The problems are tinted lenses: blue-light filtering coatings, photochromic (transitions) lenses, anti-glare coatings that shift color output, or any cosmetic tint. If you have these, bring a clear backup pair. Sunglasses must come off before the test.

Color-correcting lenses are explicitly banned by every major occupational color vision exam. Examiners are trained to identify the characteristic pink/magenta tint of EnChroma and similar products. Wearing them voids the exam and in some pre-employment contexts is considered fraud.

Verify the lighting

The clinical standard for D-15 administration is CIE Illuminant C or D65 daylight at 6000–7000K with CRI ≥ 90. Standard warm office LEDs (CRI 70–80) can artificially worsen red-green discrimination, particularly in the red end of the spectrum. This isn't a trivial effect — it can push a mild deuteranomalous candidate from pass to fail.

You probably can't politely demand a lighting audit. But you can ask: "Is this test booth using daylight-balanced lighting?" If the examiner says yes, you're in good shape. If they shrug, that's actually useful information for a potential retest appeal later. Take the test, note the conditions mentally, and if you fail by a small margin, raise the lighting question with the medical reviewer.

These are the things borderline candidates get wrong. None of them substitutes for color vision, but they prevent unforced errors.

1. Don't rush

The D-15 is not a speed test. The standard administration allows 2 minutes per eye, but most examiners will let you take longer if you're working steadily. People who rush look at two caps that "feel similar" and slot them in next to each other — which is exactly the kind of medium-distance error that creates a major crossing on the score sheet. Slow comparison reduces random errors significantly.

2. Use the start and the end

The reference cap is fixed. Place the cap that most closely matches the reference, then work outward from both directions: find what comes after, find what should come right before the reference (which is the last cap on the wheel before looping back). Working in from both ends gives you two anchors, which makes the middle section much easier than starting from one end and hoping you don't drift.

3. Watch for color fatigue

Staring at the cap set for 2+ minutes causes your retinal cones to adapt — colors begin to look less distinct, and the caps start to "merge" perceptually. If you feel stuck halfway through, look at a neutral white or gray surface for 10–15 seconds. Your cone sensitivity resets and the next caps will look noticeably clearer. This is a real perceptual phenomenon, not a placebo.

4. Compare both adjacent and non-adjacent caps

Don't only check the cap right before the one you're placing. Glance at the cap two or three positions back too. People with mild deficiencies make characteristic errors where two adjacent placements look fine in isolation but the trend across three or four caps is wrong. Reviewing the sequence as a whole catches this.

5. Adjacent swaps are okay — major crossings are not

If you're not sure whether two caps are X-Y or Y-X, don't agonize over it. Adjacent swaps don't count as failures in any standard D-15 scoring rubric. The errors that fail you are the ones where you place a cap from one side of the color wheel next to a cap from the opposite side. Pick whichever order feels right and move on.

There is no universal "pass" threshold for the D-15. Every agency sets its own. Knowing your specific employer's rules is more useful than knowing the test itself.

Standards change. The FAA's 2025 D-15 removal is a recent and consequential example. Always confirm current requirements directly with your hiring agency or aviation medical examiner before you sit the test.

Failing the D-15 is rarely the end of the road. It just changes the next step.

Most likely path: retesting or alternative tests

The D-15 is itself usually a second-chance test. If you fail it, the next test depends on the agency:

• • Police: often a field test (identifying car colors, clothing descriptions at distance). Can sometimes substitute for D-15 failure.
• • FBI: Cone Contrast Test (CCT) or anomaloscope review.
• • Military: FALANT (Farnsworth Lantern Test) or WCCVT — both significantly less strict than D-15 for some MOS.
• • Aviation: CAD or Waggoner CCVT (the new FAA-approved tests).

Waivers and appeals

Some agencies offer formal waiver processes — particularly for non-aviation, non-combat roles. For US police, this varies drastically by department (municipal departments are often more flexible than state or federal). For the military, color vision waivers exist but are mostly granted for support roles, not aviation or special operations.

Reframe: what jobs are open?

A color vision deficiency restricts some careers but not most. See our Jobs for Color Blind People guide for a comprehensive list. If you're worried about a military path, see Military Color Blind Requirements by Branch for what's actually available with various deficiency levels.

You can find online communities discussing techniques to pass color vision tests when you actually have a deficiency: memorizing cap positions from practice tests, using luminance cues, even tinted contacts.

Two things to consider. First, the test exists for a reason. Police officers identifying suspects by clothing, military personnel reading color-coded ordnance, pilots interpreting cockpit indicators — these are situations where a wrong color call has real consequences. Second, a 2018 study published in Optometry and Vision Science (PubMed 29683989) directly investigated whether subjects could learn to pass the D-15 through practice. Some did, by exploiting luminance cues, but the underlying color discrimination didn't change.

If you pass a color vision exam through workarounds and later make a color-related error on the job, the test result becomes a liability. The right path for borderline candidates is to control test conditions honestly (sleep, lighting, no rushing), take the test on your real ability, and let the agency's waiver and alternative-test processes do their job.