Why nobody could agree on the color of that dress on X In 2015, a photograph of a dress went viral, dividing viewers over whether its colors were blue and black or white and gold. This optical illusion highlighted differences in human color perception The dress is black & blue, but here's why you can't tell TJ Kelly Ten years ago, a photo of a dress posted on Tumblr sparked a massive debate: was it blue and black or white and gold? Millions argued online, and even celebrities joined in. Scientists later explained