Is the blue you see the same as the blue I see?
This question fucked me up when I was a kid. Obviously, it’s one of the world’s most common stoner thoughts, but it’s also a fundamentally natural thing to want to know: how much of our reality is shared? What does it feel like to see the world as somebody else?
Eventually, I stopped asking it – the answer seemed so fundamentally unknowable that it seemed like a waste of time. Maybe the thing you call “red” is a sensation I can’t even fathom. Maybe our universe is just a brain cell in a much larger organism and also all of this is happening in a dream. What am I supposed to do about it?
But what if the answer is knowable? Or, at least, what if there are parts of it that can be studied? Recently, I sat down to chat about this with Dr. Simon Cropper, who researches perception at the University of Melbourne. He specialises in visual neuroscience, and is one of the best-equipped people in Australia to talk about how people experience colour.
When I first asked him the question, he laughed and was like, “that’s a massive area of philosophy.”
Of course, we can’t go inside someone else’s head and confirm that they experience the same things that we do. Also, frustratingly, our ability to communicate what a colour is “like” using language is pretty limited: it’s hard to effectively describe the experience of a colour without just…using the name of the colour. But we can measure how people behave in response to stimuli and make some pretty fair guesses.
In the simplest sense, Simon tells me, the answer is no – we don’t experience colour the same way. All sensations we have are unique to us.
Every sight we see is the product of our personal physiological and cognitive systems. We’re born with slightly different bodies that have different eyeballs, with different densities of rods and cones in the retina. Of course, a colour-blind person, who has fewer cones, experiences colour differently than someone who has more cones – but the world isn’t as binary as “colour-blind” or “non-colour-blind.” Even within these populations, there’s variation. Sometimes there are even slight colour-perception differences between one person’s eyes – like your right foot can be half-a-size bigger than your left, one eye might see the world as a little warmer than the other.
And this is all happening at a very, very early layer of the visual system. We lose the initial image that hits our retinas almost instantly, and our neurons have to make split-second decisions about what signals are relevant enough to be passed on and what’s just noise. Once we have enough data our brains are able to piece it together, compare it to our past experiences and give it meaning. Our visual systems have to very quickly sort through an immense amount of raw data to make sense of the world – and they don’t always come to the same decisions.
This, Simon said, is why some of us saw the infamous Dress as blue and black, and others saw it as white and gold – it’s not just an optical illusion, but a tangible example of our brains taking a noisy image and making different calls about what the data means.
These layers and layers of small (or sometimes large) differences add up, and place us each in our own uniquely-constructed realities. And still – people mostly agree about the major parts of our environment.
“I have my reality and you have yours,” Simon says, “but we’re very good at figuring out how they fit together.”
Most of us see something we agree is blue, even if we’re not experiencing it the same way. We can say “the door is over there,” and it means something. Simon and I were able to agree to meet at a specific coffee shop and, as different as our eyes and brains may be, share enough visual cues to each find our way there – which is, in its way, a tiny miracle.
And, importantly, our systems want to synchronise into a type of "normal" state. When something shifts, our visual system tries to reduce it, normalise any drastic differences, and use our experience to predict missing visual information.
I mention to Simon how, whenever I’ve had a contact lens fall out during the day, my vision is messed up for a little – and then eventually, my brain kind of figures out what's going on. My good eye takes over, and the world becomes mostly clear again. Simon wasn’t familiar with this exact phenomenon, but it checks out to him: the part of my brain that wants an image to make sense can overpower the part that’s actually collecting raw data and create the impression of clarity with relatively sparse information.
One of the problems Simon runs up against as a lecturer – and that I’m running up against now – is that asking questions about colour is fun but answering them is actually boring and hard.
A lot of what we know about colour perception comes down to more technical physiology which isn’t nearly as enjoyable as passing a blunt to your friend and imagining life as a mantis shrimp who can perceive the world through 12 colour channels (absolutely dominating the typical human's pathetic 3 channels).
I’ve drafted and thrown out many paragraphs about colour spaces and unique hue experiments, but what I think matters is this: we understand a little bit about how our bodies process visual stimuli, and a little bit about how we actually experience colour – and these two frameworks don’t entirely match up. This makes answering questions about whether we see blue the same way hard because we don’t entirely understand how any of us see blue in the first place.
We haven’t found a perfect, physical counterpart in the body that explains the way that we perceive colour – although we can pretty safely assume it doesn’t look exactly the same for everyone. This matters, because if we were able to 100% understand anything in the brain, colour might be it.
“Colour is actually a very simple sense,” Simon tells me. “We obtain it very young, and we have extremely specific language to label it. We’re able to talk about it quite easily and effectively. And still: We can’t find the bit of the visual system that’s like, ‘That’s it! That’s the bit that mediates all this behaviour.’ We just have not found it. It looks like it’s a combination of certain areas. So if I can’t confidently say that this is the system that mediates this very early sense of colour, then it's clear to me that to try and find the bit of the brain that mediates hunger, love, or anger – all of these more complex things – we should probably be very cautious.”
Damn. I talked to the man who was supposed to make me understand the physiology of colour and now I don’t understand the physiology of anything.
Who really knows how much the blue I see looks like the blue you see? Who knows if I experience anger the same way you experience anger? Our brains are just winging it, trying to decode this full-colour phenomenon in real time and simultaneously developing theories about how they just did that.
Maybe we're all living in slightly different realities.
But it seems like we’re finding a way to make it work.