By now, you’ve all heard about The Dress: a piece of clothing with fabric that seems to shift from blue and black to white and gold depending on who’s looking at it.With over half a million notes on Tumblr and nearly 40 million BuzzFeed views, everyone is talking about it – even ophthalmologists. Shortly after the photograph of the dress went viral, ophthalmologists took to the media in droves to explain the phenomenon. According to Julia Haller, Ophthalmologist-in-Chief at Wills Eye Hospital, Philadelphia, PA, USA, there are two main theories vision scientists are suggesting for the dress’ mysterious power – it’s either in the eye or in the brain.
One possibility is that the image hits the “sweet spot” – the wavelength where rod and cone photoreceptors share duty. There’s also a tiny level of variability in photoreceptor function between individuals, so those who perceive the dress as blue and blackmay have cones that function slightly differently to those people who see it as white and gold, or they may just be relying more heavily on their rod cells. It’s likely not just the photoreceptors themselves that are responsible for the effect, though – ophthalmologists at the 38th Annual Macula Society meeting in Scottsdale, AZ, USA, think that contextual processing in the brain might also play a part. The picture was taken under some pretty serendipitous lighting conditions– some brains perceive it as overexposed, and therefore color-correct to “see” blue and black – whereas others, thanks to the Purkinje effect, perceive it as a white and gold dress in dim light. Contextual processing can be manipulated – try changing the brightness on your monitor, or exposing your eyes to bright or dim light before looking at the picture, and you may even see the colors “change.” The dress was actually blue and black, but the facts aren’t nearly as interesting as the spotlight The Dress is shining on visual processing.
