It caused a stir about three years ago. Someone posted a badly exposed picture of a dress online and it immediately went viral. The reason? Half of the people viewing the dress saw it as gold and white, while others saw it as black and blue. It was an interesting result for an optical illusion, a near-perfect bimodal distribution, and many theories were put forward to account for the effect.
Eventually, most settled on the explanation that it was something to do with the way the individual viewing the photo perceived the light-source to be coming from and the internet pretty much left it at that. Psychologists haven’t left the dress alone, however, especially those interested in cognition and visual perception. In fact, about 25 papers have appeared in the top psychology journals exploring the phenomenon, many documenting at times quite ingenious experiments trying to get to the bottom of things. A really thorough new review paper by Martin-Moro and his colleagues presents a good analysis of the research on the dress to date and reaches the surprising – but actually quite logical – conclusion that there is probably no single cause of these perceptual differences.
For some of us, it is the perceived light source, while for others it is more to do with individual differences in how consistently (or not) our brains process the same colours on different occasions. There are also individual differences in the actual structure of the front-end of the eye that can account for this, as well as in past experiences with certain colours and colour combinations. One of the more interesting sources of the difference though appears to be variations in the areas of the brain that we typically process visual information with and whether those areas are literal of just interpretive. The latter seems to be associated with seeing the dress as gold. Most importantly, our first impressions stick – no amount of experimental manipulation is going to easily shift that initial perception – if we see it black and blue first time round, we probably always will.
So there you go… a humbling experience for perceptual psychologists because what the Martin-Moro paper is really saying is that we don’t really know the cause because there probably isn’t one single reason why some see gold/white and others black/blue. I do know one thing for certain, though – whoever took that photo and posted it online has generated a lot of papers in good journals for academic psychologists!