Dr Paul Knox is a Senior Lecturer in the University of Liverpool’ s Department of Eye and Vision Science.
“Colour isn’t something that exists in the world. Different wavelengths of light exist and can be observed but colour is something we make up inside our heads.
“What meets the eye is light at given wavelengths that then stimulates several distinct pathways that process these different wavelengths.
“That’s what the brain interprets as colour but its complicated by things like the device you may be viewing the photograph on, the lighting in which you’re viewing the photograph and what’s going on inside your head; your own expectations.
“You might not expect to see gold in the dress so that would bias the eye towards seeing the colour.
“Different people can look at the same thing, particularly if it’s a photograph displayed on a monitor or phone and claim they are seeing very different things.
“In one sense they are wrong, they are looking at the same thing with the same wave lengths entering their head. In another sense they are absolutely right.”