Two people are looking at a picture of the same dress on the same screen. When asked ‘What color is this dress?’ they might give entirely different answers. Some people see a white dress with gold trim. Others see a blue dress with black trim. Others see variations. The viral picture set people at odds and, frankly, spread confusion.
No, we’re not all being fooled. It seems our hardworking brains are merely interpreting the image differently. I imagine this happens a lot, but we rarely think to ask someone else ‘What color do you see?’
My favorite explanation for what’s going on says our visual system is making an executive decision about the light quality in the room where the dress is pictured. This explanation says in the moment we first glance at the picture we subconsciously assess the room to be brightly lit or shadowy, then we use that judgment to define the dress’ color.
Say you warm up food in a white bowl. You might see the bowl in the shade of a dark kitchen, the bluish electric light of the refrigerator, and the warm orangey glow of a microwave all in the space of a few minutes. But your brain has already judged the bowl to be white; in the different light qualities the brain filters out what it believes to be extraneous colors in order to help you see the bowl as white. Despite different illumination conditions, we perceive a constant shade or color. It would be alarming to have our eyes register a change from gray to blue to orange in a short time span. Our visual system helps us understand ‘It’s a white bowl of course, and it’s reflecting the light from the microwave.’ This system is not by any means perfect, but it is very impressive when you consider the amount of information we take in with a mere glance.
When I look at the dress my brain interprets it as blue with black lace trim. If I’m more specific: blue verging toward lighter and shinier blue due to material/lighting and black lace verging toward lighter black or brown due to material/lighting. I’m discounting the warm colors because my brain believes the background is warmly lit. For people like my parents, who both see white with gold trim, perhaps their image discounts the cool colors because their brains believe the background implies shadows. The situation is further complicated because the quality of the picture does not give us a lot of context to work with, and we’re evolutionarily accustomed to interpreting daylight quality (not indoor cellphone-captured light quality).
This explanation speaks to me because of FrontierScientists’ work with Arctic ground squirrel researchers. Their work suggests that Arctic ground squirrels use minute differences in light color or quality to set their internal clocks.
At noon, the Sun is high in the sky and the sunlight that reaches the ground is bluer in color than at sunrise or sunset, when sunlight filtering through Earth’s atmosphere creates light appearing redder in color.
Discerning those color differences, and telling the time of day, require much more subtlety during the Arctic summer. Because of the Earth’s tilt, at very high latitudes the Sun never sets below the horizon during the summer.
In the land of the midnight sun, animals like reindeer and ptarmigan generally let their schedules run free; they eat when they’re hungry and sleep when they’re tired. The Arctic ground squirrels studied by Loren Buck, professor of Biological Sciences at the University of Alaska Anchorage, are an exception. “When the sun is above the horizon for 24 hours a day[,] and for weeks and even months[,] how do animals maintain their rhythmicity?” he asked. Even though the animals have an extremely limited time frame to bear young and to eat enough to prepare for the next winter’s long hibernation, Arctic ground squirrels follow a persistent schedule to determine when they leave their burrows to forage for food. “They poke their head out of their burrow in mid summer around 7 o’clock in the morning and they call it a day at about 7 o’clock at night,” Buck described.
“Their circadian clock, their master oscillator in the brain is guiding their daily rhythms, and there’s something in the environment that is cueing or entraining that clock,” Buck said. It could be that the Arctic ground squirrels’ visual systems are particularly adept at detecting subtle differences in the red and blue qualities along the chromatic axis of sunlight. They might take advantage of those color cues to keep their internal clock on track.
Scientifically, we’re very interested to know how the Arctic ground squirrel’s impressive internal clock stays on track. “So many of the disease states – pathologies – that are exhibited by humans today are characterized by a breakdown in clock function,” Buck described. He listed seasonal defective disorder, cardiovascular disease, diabetes, alzheimers, and old age senility. “Virtually any pathology that you can think of is tied to clock function.” Decoding how Arctic ground squirrels regulate their internal clock function can help us decode and one day treat a wide range of human problems.
Learning why humans see that dress – which is, in fact, blue colored with black trim – so differently might teach us more about our own physiology. Until then it serves for an interesting discussion and a fun jumping point into optical illusions.
Laura Nielsen 2015
Frontier Scientists: presenting scientific discovery in the Arctic and beyond
- Interviews with Loren Buck, 2013 & 2014
- ‘1492: Dress Color’ XKCD comic by Randall Munroe, xkcd.com, Explain XKCD (Feb 27 2015)
- ‘Guys please help me – is this dress…’ Swiked, Tumblr (Feb 25 2015)
- ‘Scientists can mostly explain the color-changing dress. But there’s one big mystery.’ Brad Plumer, Vox (Feb 27 2015)
- ‘The Science of Why No One Agrees on the Color of This Dress’ Adam Rogers, Wired (Feb 26 2015)
- ‘What colour is the dress? Here’s why we disagree’ Michael Slezak, NewScientist (Feb 27 2015)