Underlying the Great Dress Debate of 2015 is a fascinating example of how the brain interprets the world around us.The dress. In the future, will you remember which side you were on?
Would you like to have an argument with your colleagues this fine
Friday? Just ask them what colour the dress above is. Some people say
white and gold, whereas others claim it’s clearly blue and black. This
rift in opinions has caused many people to doubt the sanity of
themselves and their friends. Excitingly, it also offers some sort of
insight into the famous old philosophical question: “is your red the same as my red?” But why are people so divided by this?
It appears to be because of different interpretations of how the
scene is illuminated. The brain automatically “processes” visual input
before we consciously perceive it. Differences in this processing
between people may underlie The Great Dress Debate.
In our everyday lives, there are many changes in the colour of the
light illuminating our surroundings. For example, the yellow glow of an
incandescent light bulb versus the blue-ish hue of a fluorescent light.
The light that an object reflects to the eye is a combination of both
the colour of the object itself and the spectrum of the light source,
which may vary. The brain is able to disentangle these two things and
decide what colour the object is. Simply put, objects appear the same
colour even if the light illuminating them changes – a concept known as colour constancy.
So, how does the brain keep colours constant? One way is by using
reference points. For example, say you know your mug is white, but the
light being reflected from the mug is slightly red. The brain can then
discount a certain amount of red tint from the rest of the scene you are
seeing. Other contextual knowledge may come into play, for example you
are drinking coffee by the window at dawn. It makes sense for the light
to be red-tinted as the illumination source is the sunrise. This is
known as top-down processing. All of our perceptual experiences are informed by this kind of processing, resulting from context and previous knowledge.
This is possibly something you’ve never thought about or been aware
of before - you may well underestimate just how much the lighting in our
world changes, because your brain compensates for it so well. This
happens automatically without any conscious awareness. But, colour
constancy is not perfect. In The Dress photo, there aren’t many
cues or reference points to tell us the properties of the light source.
This leads to ambiguity and the possibility of different
interpretations.
This image is a fascinating example of something on the edge of a
perceptual boundary. Some people’s colour constancy is calibrated so
that their brains tell them they are seeing gold and white, whereas some
are lead to believe they see black and blue. Of course, the colour
constancy mechanism is always learning, and due to top-down information
(e.g. reading others’ opinions) this calibration could change and lead
to another experience. This may be the driving force behind people
experiencing a shift from seeing white and gold to blue and black.
Imagine how the world would look without colour constancy; objects
would always be changing colour as you walked, say, through your house
at different times of the day. I am currently doing research on the
development of colour constancy in children within the Sussex Colour Group. Toddlers may experience a lower level of colour constancy than adults, making the world even more confusing for them. It has also been suggested that Monet was somehow able to disregard this automatic process in order to paint scenes showing how light progressed over the day. To most of us, the change in the colour of light over the day would be less noticeable.
There now appears to be good evidence
that The Dress is in fact blue and black (but it’s always good to keep
some scepticism regarding information on the internet). Therefore,
arguably, people who originally saw it this way have better colour
constancy. They were able to take cues from the background and
compensate for the very unnatural illumination. There is evidence that
people with good colour constancy also have better working memory (a part of short term memory dedicated to immediate perceptual processing) and that these two processes may be related.
Those who originally saw The Dress as blue and black should not be
too smug, though. Some may argue that colour itself is just a construct
imposed by the brain to make sense of the world. What enters the eye is
just a spectrum of wavelengths of light, we turn that into something
with category boundaries and labels and connotations. But one thing’s
for certain; The Dress is a brilliant example of how breaking the
perceptual system helps us to learn more about how our brains work.
