Original Educational Screen
Symbol Contrast Screen
Identify simple symbols using red-green and blue-yellow contrast pairs. This original activity supports self-exploration; it is not the HRR test and is not diagnostic.
Before You Start
Prepare Your Screen
Symbol Screen is an educational, screen-based activity. The result can be affected by your display, lighting, and colour settings.
- Set brightness to at least 75% and avoid strong glare on the screen.
- Turn off Night Shift, blue-light filters, colour filters, and adaptive display modes.
- Use a tablet, laptop, or desktop if possible. Do not use this result for work, licensing, or medical decisions.
Removing the reading step
Pseudoisochromatic activities place a figure within a field of coloured dots. The figure and background are designed to differ mainly by hue rather than by a strong outline. One important design choice is whether the participant must read a digit or recognise a simple symbol.
Naming a digit adds a reading task to the visual one. A young child or someone unfamiliar with Western numerals may give a different answer for reasons unrelated to the colours.
Using a circle, cross, or triangle reduces that reading requirement. The participant can name or select a familiar symbol. ColorVision’s symbols and colour pairs are original and have not been validated against a clinical symbol-plate book.
Two colour-pair families
This activity includes red-green-oriented and blue-yellow-oriented colour pairs. Those labels describe how the items were designed; they do not mean the activity can classify a medical condition.
Red-green items explore whether a symbol stands out when its foreground and background use selected red-green-oriented hues.
Blue-yellow items repeat the same task with selected blue-yellow-oriented hues. Screen technology and blue-light filters can alter these colours substantially.
Responses from either group cannot reveal whether a difference is inherited, acquired, temporary, display-related, or simply an input mistake. A new or changing difference in real-world colour perception should be assessed professionally without waiting for an online result.
Reading the outcome
The screen reports which items you identified as expected and whether misses cluster on the red-green or the blue-yellow axis.
Identifying an item means its symbol stood out for you on this device in the conditions of that attempt. A group of different responses shows which colour pairs were harder within this activity, but it does not establish colour discrimination for real-world tasks or identify a deficiency. Scattered differences can reflect testing conditions rather than colour vision — check brightness, disable adaptive colour, and try again.
Limits worth stating plainly
The symbols are deliberately simple and the set is short. No sensitivity, specificity, or clinical threshold has been established for this original activity. Identifying every symbol therefore does not establish typical colour vision.
Display limits affect every browser-based colour activity. Brightness, panel gamut, ambient light, browser colour management, and blue-light filters can all change whether a symbol stands out. Turning adaptive settings off may reduce variation, but it does not make the result diagnostic.
And as with every activity on this site, this is educational screening. It is not a diagnosis, and it is not accepted for occupational, licensing or medical purposes. Those require supervised clinical testing.
For a version designed specifically around young children’s attention and motor skills, see the shape activity for children. For background, types of colour blindness explains the protan, deutan and tritan distinction, and tritanopia covers the blue-yellow axis in detail.
Got Questions?
Frequently Asked Questions
Everything you need to know about colour blindness tests, how they work, and what to do with your results.
Why use symbols instead of numbers?
Digits require literacy in a specific numeral system. That excludes young children, adults who do not read Western numerals, and anyone being screened in a language they do not share with the examiner. Shapes such as a circle, square, triangle or star can be named, pointed at, or traced by almost anyone, so the same colour information can be tested without a reading step in the way.
Is a symbol screen less accurate than a digit screen?
No accuracy comparison has been established for these two original browser activities. Symbols remove the number-reading requirement, while the digit activity offers a longer set of figures. Neither is a validated clinical test.
It includes blue-yellow items. Why?
They let the activity present a second family of colour contrasts rather than only red-green pairs. A browser response cannot establish a tritan deficiency or identify the cause of a visual change.
What should I do with a blue-yellow finding?
Treat it only as a response within this activity. Display calibration and blue-light filters can strongly alter these colours. If you have noticed a new or changing difference in your vision, speak with an optometrist or ophthalmologist regardless of the browser result.
Can I use this to screen someone else?
You can, informally. Sit where you can see their responses without cueing them, keep the room lit evenly, and do not name the shapes yourself or react to answers. Record what they report rather than whether you think it is right. This is a conversation starter with a professional, not an assessment.
Does this work on a phone?
It runs on a phone, but a larger screen may make the figures easier to view. Phones often apply automatic brightness and colour adaptation. Whichever device you use, the result remains educational rather than clinical.
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