#TheDress became the most viral internet phenomenon of 2015 when a photo of a dress sparked a global debate: was it blue and black or white and gold? The optical illusion divided the world and generated scientific discussions about perception.
The photo was posted to Tumblr on February 25, 2015, by a Scottish woman whose friend wore the dress to a wedding. The disagreement about its color went viral within hours. Within 48 hours, the photo had been viewed 28 million times.
The answer: the dress was physically blue and black (confirmed by the manufacturer), but depending on how brains interpreted the lighting in the photo, people saw different colors. It became a case study in how individual perception varies based on assumptions about light source and shadow.
Celebrities weighed in. Scientists published papers. The dress was discussed on morning shows, late-night TV, and in peer-reviewed journals. It united the internet in a rare moment of lighthearted mass participation.
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