#Thedress and your optometrist - the scientific voice of reason

It’s not every day the College of Optometrists shares a news platform with Taylor Swift, Kim Kardashian and Julianne Moore, but Friday was not just any day.

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Author: Daniel Hardiman-McCartney MCOptom, Clinical Adviser
Date: 2 March 2015

It’s not every day the College of Optometrists shares a news platform with Taylor Swift, Kim Kardashian and Julianne Moore, but Friday was not just any day. A social media sensation was spreading around the world in the blink of an eye. For those who missed it, the internet viral sensation was #thedress. An innocuous photograph of a dress which divided more than 24 million people in less than a day. 

The question, a simple one you may think, was whether the dress in the photo was blue and black, or white and gold. Pretty straightforward? Well no, far from it. As the headline of the Daily Mail read, “Debate rages”. Taylor Swift saw the dress was "obviously" blue and black. "What's the matter with u guys, it's white and gold," countered Julianne Moore. Kim Kardashian was seeing white and gold but to husband Kanye West, it was solidly blue and black. "Who is color blind?" Kardashian asked the world of Twitter?  All weighed in on the debate and around the world no one could agree.

So there is no right or wrong answer; both interpretations are perceptual constructs from the photograph.

Online there were lots of differing explanations (many wrong) from photographers, lighting engineers, ophthalmologists, vision scientists, philosophers and of course celebrities, as to why there was such divided opinion on the colour of the dress. Step in the College of Optometrists, ‘the scientific voice of reason’. 

Optometrists are certainly qualified to provide a definitive answer to Kim Kardashian’s question, who is colour blind?  As the College explained on the BBC News, when people see different colours in the dress, it is not because of colour deficiency. So what is going on? Well the reason why people are seeing different colour dresses is because the photograph is a contrast illusion, specifically a colour contrast illusion. 

Why is it so striking? Well, in my opinion, there are two key features that make this illusion so effective. First, there is a rich yellow light shining onto the dress, resulting in shades of gold and orange illuminating from the black and washing out the blue. As optometrists, we know how our visual system adjusts throughout the day to ensure a white sheet of paper remains white in our minds despite changes in the daylight colour; this effect is known as colour constancy. So when viewing this image, our visual system has to decide on how much to discount the colour of the illuminance, due to this rich yellow light. Secondly, we perceive the colour of both the dress and the light source by looking for clues from the other colours and objects in the picture.

The picture is ambiguous: the bar code strips of material running through the dress give no clues to our visual system, resulting in the image being interpreted in one of two ways, blue and black or white and gold. So there is no right or wrong answer; both interpretations are perceptual constructs from the photograph. We do however know from both the wearer and the retailer that the dress is in fact blue and black. Interestingly, some who originally viewed the dress as white and gold found themselves able to perceive blue and black once they knew the ‘true’ colour. I look forward to following the academic discussion. 

I've never seen a photo like this before where so many people look at the same picture and see two such dramatically different sets of colours. For all the different variables to be present in one casual snap is extraordinary, perhaps a one in a million shot. Whatever we think of the newsworthiness of the story, as optometrists we have the knowledge to understand the wonder of our vision, and through this unique image, an opportunity to share it with our patients. The 24 million people who viewed the picture on Friday gained an insight into how truly remarkable their visual perception system is. By any measure, that’s a good day for science.

Daniel Hardiman-McCartney FCOptom
Clinical Adviser, The College of Optometrists

Daniel graduated from Anglia Ruskin University, where he won the Haag Strait prize for best dissertation. Before joining the College, he was Managing Director of an independent practice in Cambridge and a visiting clinician at Anglia Ruskin University. He has also worked as a senior glaucoma optometrist with Addenbrooke’s Hospital in Cambridge, with Newmedica across East Anglia and as a diabetic retinopathy screening optometrist. Daniel was a member of Cambridgeshire LOC from 2007 to 2015 and a member of the College of Optometrists’ Council from 2009 to 2014, representing its Eastern region.  

He is Clinical Adviser to the College of Optometrists for three days each week, dividing the remainder of his time between community practice, glaucoma shared care clinics and providing consultancy to Specsavers. Daniel is a passionate advocate of the profession of optometry, committed to supporting all members of the profession and ensuring patient care is always at the heart of optometry. He was awarded Fellowship by Portfolio in December 2018.


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