Do you see blue or green? This viral test plays with color perception

It started with an argument over a blanket.

“I’m a visual neuroscientist, and my wife, Dr Marissé Masis-Solano, is an ophthalmologist,” says Dr Patrick Mineault, designer of the viral web app ismy.blue. “We have this argument about a blanket in our house. I think it’s unambiguously green and she thinks it’s unambiguously blue.”

Mineault, also a programmer, was fiddling with new AI-assisted coding tools, so he designed a simple color discrimination test.

If you navigate to ismy.blue, you’ll see the screen populated with a color and will be prompted to select whether you think it’s green or blue. The shades get more similar until the site tells you where on the spectrum you perceive green and blue in comparison with others who have taken the test.

“I added this feature, which shows you the distribution, and that really clicked with people,” says Mineault. “‘Do we see the same colors?’ is a question philosophers and scientists – everyone really – have asked themselves for thousands of years. People’s perceptions are ineffable, and it’s interesting to think that we have different views.”

Apparently, my blue-green boundary is “bluer” than 78% of others, meaning my green is blue to most people. How can that be true?

Our brains are hard-wired to distinguish colors via retinal cells called cones, according to Julie Harris, professor of psychology at the University of St Andrews, who studies human visual processing. But how do we do more complex things like giving them names or recognising them from memory?

“Higher-level processing in terms of our ability to do things like name colors is much less clear,” says Harris, and could involve both cognition and prior experience.

The science may be tricky, but ismy.blue’s intuitive interface and visualised results were instantly engaging, leading to over 1.5m visits since its launch in early August.

“I’m not super surprised that it struck a chord because people want to understand how others see the world,” says Mineault.

Clearly there’s a widespread fascination with perception and subjectivity. Many of us remember how The Dress went viral in 2015 because it looked white and gold to some and blue and black to others.

Most differences in color perception are physiological, like color blindness, which affects one in 10 men and one in 100 women. Others, however, may be connected to aspects of culture or language.

The Sapir-Whorf hypothesis of linguistic relativity, popularised in the movie Arrival, suggests that language shapes the way we think, and even how we perceive the world. In the 1930s, Benjamin Lee Whorf argued that the world consisted of “a kaleidoscopic flux of impressions organised … largely by the linguistic systems of our minds”, pointing to, for instance, the Inuits’ multiple words for “snow” as an example of differences in cultural perceptions.

Although this theory continues to be hotly debated throughout linguistics, psychology and philosophy, language does inform how we communicate ideas. There’s no word for “blue” in ancient Greek, for example, which is why Homer described stormy seas as “wine-dark” in The Odyssey. By contrast, Russian has distinct words for light blue and dark blue. However, recent research suggests a greater vocabulary may only be beneficial for remembering colors and not for perceiving them.

Before you fight online about whether a particular shade is aqua or cyan, it’s important to note that ismy.blue’s results have limitations. The slightest variation in viewing conditions influences color perception, which is why vision researchers take such care when designing experiments. Factors like the model of your phone or computer, its age, display settings, ambient light sources, time of day and even which color is presented first in the test will all play a role in your responses.

Related: #TheDress one year on – eight things we learned from the viral phenomenon

Night modes in particular increase the redness of a device’s screen, causing blues to appear greener. To see if this was influencing test results, Mineault separated the data into two groups: before or after 6pm. The effect was immediately apparent, especially on devices with built-in night modes.

So what’s the point of ismy.blue if it’s so variable? In the end, it’s just entertainment. But if you’d like results with a little more equivalence, Mineault suggests doing the exercise with others on the same device, so that “everybody’s in the same lighting and the same place”.

Although Mineault doesn’t have any plans to publish the results, ismy.blue is a great example of citizen participation in science. For instance, since 2010, tens of thousands of people have played the online puzzle game Fold.it, which helped scientists at the University of Washington crack notoriously difficult protein folding problems. The mobile app Sea Hero Quest, which aimed to learn more about navigation in people with dementia, had more than 4 million players before the experiment ended in 2017.

Science is historically insular, focusing almost exclusively on the WEIRD (Western, Educated, Industrialized, Rich and Democratic). Opening research up to the public better equips scientists to understand the amazing diversity of human experience. “Most vision scientists have always gone ‘we’re all the same’, [but] there’s all sorts of interesting evidence showing that vision can be different across cultures,” says Harris.

Citizen science also does wonders for the relationship between an often-stuffy academic community and the wider public.

“It’s a lot of work to communicate something to someone who’s not in your subspecialty, but I think that’s where the innovation happens,” says Mineault.

One question remains, though: what color is the blanket?

“We’ve taken the test a bunch of times,” says Mineault. “As soon as there’s a little green in there, I call it green”; his wife sees blue.

The solution? Maybe just buy a new one.

• Ben Thompson is a behavioural neuroscientist, writer and artist