• 23 February 2023 (Nature.com)

Neuroscientist Anil Seth draws on his 20-year career to reveal that the mystery of consciousness need not be beyond science.

• Emily Cooke

Anil Seth recalls standing in front of a bathroom mirror aged eight or nine, and suddenly understanding that he would die one day. That realization made him wonder about where he came from, and why he was who he was. Those childhood thoughts about consciousness developed in his teenage years, resulting in debates with friends about free will and the mind. Seth now investigates such questions as a neuroscientist, and is the author of the 2021 book Being You: A New Science of Consciousness (Faber & Faber). His 2017 TED Talk, ‘Your brain hallucinates your conscious reality’, has had more than 13 million views. Here he talks to Nature about his career and book, and about the other public-engagement activities he undertakes as professor of cognitive and computational neuroscience at the University of Sussex near Brighton, UK.

Tell us about your book.

Consciousness is linked to subjective experience, which isn’t the same as being intelligent or having language or writing poetry. I want people to understand that the science of consciousness is alive and well. It doesn’t mean we will find the answer to it, but we can make a lot of progress in understanding it.

I make three arguments in the book. The first is that consciousness can be addressed by science. I divide it from one big scary mystery into a few smaller, more-tractable ones. For example, how can we explain the difference between various levels of consciousness — such as between general anaesthesia and wakeful awareness or falling into a dream sleep, a psychedelic state and so on.

The second argument is based on how we perceive the world around us — the idea that we live in a controlled hallucination and that our experiences of the world don’t give us direct, unfettered access to whatever’s out there. The neuroscience theory here is that the brain is continually generating predictions about our surroundings.

The third argument is that the self is another kind of controlled hallucination, whether it’s the experience of free will, of having a body of emotion, of mood — all different kinds of perception.

At the end of the book, I explore some of these implications for consciousness in non-human animals, and question whether artificial intelligence will become not only intelligent, but also sentient.Why women aren’t from Venus, and men aren’t from Mars

How did the book come about?

I like to talk about what I do and, perhaps unlike with some other areas of science, people are naturally curious about consciousness and more willing to listen. I have also always liked writing. When I was an undergraduate, I realized that writing is fulfilling. Through your academic career, you write more and more, be it papers, research grants or editing. I did some public-engagement work, initially giving talks, then writing short pieces for outlets such as New Scientist and The Guardian, which was extremely satisfying.

In 2016, I presented a Friday Discourse at the UK Royal Institution — the most prestigious thing I had done. (These talks were set up in their current format in 1826 as informal conversations about science with the public.) I chatted to people who were working in public engagement, including geneticist and BBC broadcaster Adam Rutherford, and I just felt then that it was the appropriate moment to write the book.

What drew you to the science of consciousness?

I started doing physics at university, mainly because it is seen as the most fundamental of the sciences and the best way to plug any gaps in understanding. But I felt I was moving too far away from the mind, so I switched to psychology and, later, during my master’s degree and PhD, to computer science and artificial intelligence.

After my PhD, a postdoctoral opportunity in brain-based robotics arose at the Neurosciences Institute in San Diego, California. I got the job, not because of my interest in consciousness, but because I could help to build biologically inspired robots.How a grisly historical accident set one neuroscientist on the road to writing a book

At that time, in the early 2000s, the institute was one of the few places where it was acceptable to study consciousness. There was a sense that the field was still predominantly philosophical and that it might be a poor career choice, because people didn’t really know what consciousness was or how it worked. However, things changed when senior academics began to talk about consciousness and to set up dedicated research institutions. I ended up staying at the institute for more than six years, working on diverse projects (it ceased its research operations in 2018). Also, living in San Diego is not bad, learning to surf and all.

It was an inspiring time, with the feeling that I had found an intellectual community. I started attending meetings of the Association for the Scientific Study of Consciousness — an international non-profit organization co-founded by the German philosopher Thomas Metzinger in 1994. The community includes some of the smartest and most interesting people I have met, from disciplines across philosophy, psychology, neuroscience, medicine and computer science. I thought, ‘this is the work that I want to do’.

I think we are all interested in ourselves, how we work and who we are, so I am grateful that I have been able to make a career out of my interest in these fundamental questions.

How did you balance writing the book with your academic career?

With difficulty. One struggle is that universities want academics to do public engagement, but do not give much credit in terms of time or teaching remission. Sometimes, the attitude is that if it is fun, then you should do it in your spare time. Good public engagement takes time, and is very important for inspiring new generations of scientists and increasing the impact of your work.Collection: Science communication

Luckily, I had an Engagement Fellowship from the UK research funder Wellcome that provided me with a break from teaching duties. However, I was still writing the book mainly in the evenings and at weekends. The rest was done ad hoc by setting myself deadlines. If you write 1,000 words every couple of days, you will soon have a book.

A key challenge was balancing what I wanted to say with what people will want to read, which is where having a good editor really helps. I was worried that, having put lots of effort into the book, it would sink like a stone and go unnoticed. However, the reception was extraordinary and exceeded my expectations.

What is your main focus now in terms of public engagement?

One current project is Dreamachine, which brought together scientists, philosophers, architects, musicians and digital designers to develop a collective, immersive art experience. It is based on the neuroscience concept that fast, flickering lights on closed eyes give rise to visual hallucinations. Last year, the installation formed part of the UNBOXED festival, a UK-wide event featuring ten creative projects that straddled the arts, sciences, technology and mathematics. During the festival, more than 30,000 people experienced Dreamachine, which is amazing. Hopefully it is reigniting people’s curiosity in the brain.

Another focus is the Perception Census, a big online citizen-science survey overseen by the University of Sussex and the University of Glasgow, UK. We’re asking members of the public to take part in a series of online, interactive tasks from the comfort of their own homes, so we can try to learn more about perceptual diversity.Collection: Spotlight on neuroscience

Over the past decade or so, there has been much emphasis on neurodiversity, the idea that there are many different ways of experiencing the world, and that this cognitive and perceptual variation enriches society. However, the neurodiversity label has come to be associated with specific conditions, such as autism or attention deficit hyperactivity disorder, ironically reinforcing the idea that if you don’t identify with a neurodivergent condition, then you experience the world as it is, in a neurotypical way.

But perceptual diversity exists among all of us. Two people might experience different colours when they look up at the sky, but they won’t know it because they will use the same descriptive words. It’s also because the differences they see are not enough to influence behaviour, and, crucially, because perceptual experience seems to be a window on to objective reality, rather than a brain-based construction. I’m now very interested in mapping out this hidden perceptual diversity. I want to know about the middle, not the extremes. Our Perception Census project is doing exactly this. If we can recognize that everyone literally sees the world in a different way, then it might become easier to accommodate the fact that others might see, and therefore believe, different things.

doi: https://doi.org/10.1038/d41586-023-00541-z

This interview has been edited for length and clarity.

(Contributed by Michael Kelly, H.W.)