“Guys please help me – is this dress white and gold, or blue and black? Me and my friends can’t agree and are freaking out,” posted one frantic Tumblr user from the small Scottish island of Colonsay. With but a few words and one shoddily captured photo, #thedress defied all odds and managed to captivate the internet for a solid 48 hours before fading into obscurity. Its fascination lay in the colors – was it blue and black, as most people saw it, or was it white and gold, seemingly the exact opposite? According to a study by researchers from the University of Bradford, the colors of the dress are whatever you perceive them to be, depending on some optical trickery.
“The confusion would have never occurred if it was not for the special colours present in the photograph, it would not have happened with other coloured dresses. The bluish and yellow colouring in the image correspond to colours that we experience naturally during the course of the day, they lay on what is known as the daylight locus,” said Professor Marina Bloj, Professor of Visual Perception within the Bradford School of Optometry and Vision Sciences.
Apart from the online histrionics, #thedress is a pretty unique photograph: The dress in question takes up most, but not quite all, of the frame, and what’s left around it is washed out due to harsh fluorescent lighting. It’s an image so perfectly designed to trick the brain and eyes, you almost have to wonder if it wasn’t done intentionally, as part of some kind of “guerrilla” science experiment.
For Bloj’s actual experiment, participants were shown a disc shaded in colors that matched those reported in the photograph. Interestingly, no pattern of “blue vs white” appeared in their tests, as with the photograph. Instead, participants reported a spectrum of colors ranging from dark blue to light blue.
“The question should thus not be whether the dress is blue or white, but whether it is light blue or dark blue,” says Prof. Dr. Karl Gegenfurtner, department of psychology at Justus Liebig University Giessen (JLU). “Despite the continuous choice of matching colours, observers are consistent in calling the dress ‘white’ when their match lies above a certain brightness and ‘blue’ when it lies below.”
It all has to do with something called the daylight locus, which causes our brains to associate certain colors with certain times of day. The sky makes us associate bright daylight with blue colors, whereas yellows and oranges are associated with evening light. Typically, we rely on points of reference to filter out this effect such that everyone perceives colors the same way – reds, greens and other colors not associated with daylight effects. Those reference points aren’t present in the photo of the dress, and so the bright light surrounding it makes it difficult for the brain to lock in on the colors.
Depending on the time of day you were viewing the image, along with the lighting in your own surrounding environment, the photo cold very well appear to be of a dark blue and black dress, or a light blue and gold one. The “blue/white” argument was likely the result of the blue sections falling against the black ones, and the contrast caused some people to assume the lighter shades of blue they were seeing were actually white.
The dress, for the record, is indeed blue and black.