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For something as intimate to our lives as perception — how we experience ourselves and the world — we know remarkably little about all the ways it can differ from person to person. Some people, for instance, have aphantasia, which means they experience no mental imagery, while others have no inner monologue in their heads, just silence. Studying what scientists now call “perceptual diversity” is part of an increasingly mainstream effort to learn more about consciousness itself.

Among the new wave of researchers who are trying to unravel the mystery of consciousness in the lab is Anil Seth. Seth is the co-director of the Sackler Centre for Consciousness Science and the author of Being You: A New Science of Consciousness. His viral TED talk in 2017 popularized the idea of consciousness as a “controlled hallucination,” which suggests that our perceptions are less like looking through a transparent window on the outside world and more like watching an internally constructed movie. When sensory data from the outside world contradicts our brain’s movie, it updates the film.

Now Seth is behind another project that aims to “paint a multidimensional portrait of this hidden terrain of inner diversity,” he told me. By studying the subtle ways perception can vary, we can understand the many different ways our brains construct our realities. That’s why in 2022, Seth and his colleagues in collaboration with the creative studio Collective Act launched the Perception Census, the largest psychological study of its kind. It aims to help bridge the divide between philosophy and science by providing experimental evidence for questions, such as how our individual minds differ, that have long been out of reach.

The online survey gives participants a series of tasks, brain teasers, and interactive illusions that each probe a different aspect of perception, such as vision, sound, rhythm, how you experience the passage of time, and even how your imagination works. It’s already reached over 20,000 participants. “Just as biodiversity is important for the health of an ecosystem,” Seth told me, perceptual diversity “is something that enriches society.”

I spoke to Seth about what the perception census is, why perceptual diversity matters, and how this all relates to the growing field of consciousness studies.

This interview has been edited for length and clarity.

What got you interested in a project like the Perception Census?

My research and [that of] many others has led to this view that what we perceive is not a direct readout of what’s there. It’s an active construction in which the brain plays an essential role. Because of the way perception works, it seems to us that we see the world and hear the world as it is — it doesn’t seem like it’s a brain-based construction. Unless you interrogate that, it’s very hard to understand that somebody might actually be having a different experience, even if they’re in the same shared objective reality.

And, of course, we all have slightly different brains. So we’re all going to inhabit different inner universes, and not a lot is known about that. With this idea of perceptual diversity, what we’re trying to do is bring back into the light this idea that, in fact, we all differ, and the differences don’t have to be very large to exist.

Is this the first time anyone has systematically studied the different ways we experience the world?

It’s definitely not the first time. There’s a long tradition of looking for individual differences. But what’s distinctive about what we’re doing is the scale, breadth, and reach.

[The Perception Census] has about 100 different things that people can do, each probing different aspects. That scale hasn’t been attempted before. That allows us to look at what the patterns are, and whether there are underlying factors that explain how different aspects of perception correlate.

Beyond intrinsic interest in learning more about consciousness, what could we do with a richer understanding of perceptual diversity?

One goal of the census is awareness-raising because people are remarkably surprised when they realize that people can have different inner experiences. But they’re also surprised just by all the under-the-hood complexity involved in this everyday miracle of just experiencing the world.

I also think it can cultivate a bit of useful humility about our own perceptions and beliefs. If we really had this understanding that the way I see things is not the way they are, then it’s easier to understand that somebody else might see something differently. In a world of increasing polarization and fragmentation, understanding that we differ, and how we differ, can build platforms for empathy and communication.

When it comes to mental health, neurodiversity is a well-established community with lots of important lobbying efforts that have done great work. But it tends to be associated with specific conditions and reinforces this normative, neurotypical view for people who aren’t neurodivergent in that way. What I’m hoping is that the census can reinforce the recognition of diversity in the normative, neurotypical range.

How do you imagine this kind of research could evolve in the future?

We can start to drill down. For instance, if we find some interesting aspects of perceptual diversity that stand out, or some factor that seems to predict diversity in different dimensions, then we might bring people into the lab. We can do more fine-grained controlled experiments, using things like brain imaging. We might begin to look at the biological mechanisms that are responsible for this diversity. We can’t do that in a large-scale survey.

Then we could also zoom out. There are limitations on what we’ve been doing. We’re only looking at people who speak English. We’re not really sampling across cultures as much as we would ideally like. Also just for very boring ethics reasons, we’re only looking at people 18 and over, so another whole range is what’s going on with the development of perceptual diversity; that can be new terrain, too.

And we’ve got 100 tasks, but that’s a small subset of the possible things we might want to ask. One of the things we were worried about was that we’re asking quite a lot of people to spend their precious attentional moments on something, so we have to make it rewarding for them. And it turns out, we have 20,000 people already, and one comment we received was that “this is what the internet is made for.”

In your book Being You: A New Science of Consciousness, you write that advances in the science of consciousness are “inaugurating a transformation in psychiatry from treating symptoms to addressing causes.” I’m curious how you think these kinds of advances might help support this transformation.

Many different things can catalyze that move. The census is, in itself, not telling us much about mechanisms. But it’s laying out the territory. By seeing what correlates with what, that will give us some indication of whether there are dials in the brain, if you like, that you can turn, and they change perception in different ways, or maybe if you turn it too far, you get something that can transmogrify into mental illness.

So you need to know the lay of the land in order to understand the kinds of mechanisms we’re looking for that may go awry in mental health disorders. More generally, consciousness research is making advances here.

Whether it’s psychedelics or computational psychiatry, there are increasingly detailed mechanistic proposals for why people have the psychiatric symptoms they do. The key thing that consciousness research brings to that is a focus on their experiences, rather than the behavioral symptoms of psychiatric and mental health disorders.

If you’d like to help chart the terrain of perceptual diversity, you can take the Perception Census here.

Oshan Jarow @OshanJarow is a Future Perfect fellow, where he focuses on economics, consciousness studies, and varieties of progress. Before joining Vox, he co-founded the Library of Economic Possibility, where he led policy research and digital media strategy.

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