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26 February 2022

Is reality a hallucination? The neuroscientist Anil Seth thinks so

After decades of research into the mysteries of consciousness, the British academic has reached a radical conclusion – by way of meditation, surfing and a DIY "dream machine".

By Sophie McBain

If you’ve ever undergone general anaesthetic then you have experienced oblivion, an interruption of consciousness more complete than even the deepest sleep. Whole hours or days can pass in a millisecond; it’s proof – if you need it – that you can cease to be, that the world will go on without you. Some people find this terrifying. The neuroscientist Anil Seth finds it reassuring.

In 2017 Seth gave a Ted talk that has since been viewed more than 12 million times, a mind-blowing, 15-minute distillation of his three decades of research, which ended with Seth paraphrasing Julian Barnes: “When the end of consciousness comes, there’s nothing to be afraid of – nothing at all.” It’s a sentiment he returned to in his bestselling 2021 book, Being You, and when we met recently in Falmer, East Sussex, he told me why: “When you see how fragile and precarious our unified consciousness is, of ourselves and of the world, when you see how many ways it can go wrong or just be abolished completely, you can either take that as a scary thing or a reminder to be very glad to be where you are.” He chooses the latter.

Seth, 49, was casually dressed in jeans, beige trainers and a blue jumper. His close-shaven head and quiet intensity lent him a monkish air, which he periodically punctured with a joke. We spoke in his office at the University of Sussex, where he is co-director of the Sackler Centre for Consciousness Science. (As the university will no longer be receiving new funding from the Dr Mortimer and Theresa Sackler Foundation, the centre is due to be renamed.) On the bookshelves were works on psychology, philosophy, informatics, physics, a Zadie Smith novel, poetry anthologies. Tacked to the wall was a print-out headlined “12 fucking rules of success”. (1. Do the fucking work. Don’t be lazy.)

Seth began studying consciousness in the mid-Nineties, a time when advances in computing and brain imaging were giving scientists new tools for understanding the mind. In 1994, the Australian philosopher David Chalmers outlined the challenge ahead: in a talk at the inaugural Science of Consciousness Conference in Tuscon, Arizona, Chalmers set out what he described as “the hard problem of consciousness”. How can objective, physical matter give rise to the unique, subjective experience of consciousness? How could anyone adequately describe the inimitable feeling of being you, with reference only to your brain and biology?

Philosophers and scientists have tried to tackle this hard problem in different ways. Panpsychists argue that consciousness is a fundamental quality of all matter – that a deckchair exhibits a different kind of consciousness from you or I, but is conscious nonetheless. At the other extreme, illusionists argue that consciousness is only imaginary. Seth, whose academic background spans physics, psychology, computing and neuroscience, says he has come to another, more satisfying conclusion.

[See also: From the NS archive: The work of Freud]

His research has led him to radical positions: the way you see yourself and the world is a controlled hallucination, Seth argues. Rather than passively perceiving our surroundings, our brains are constantly making and refining predictions about what we expect to see; in this way, we create our world. He points to the example of #TheDress, the viral photo of a cocktail dress that to some people appears gold-and-white, and to others as blue-and-black. In his Ted talk, Seth twice plays an audio clip of a high-pitched, distorted voice that is so incomprehensible it could be speaking any language or none at all. Then he primes his audience with the sentence: “I think Brexit is a terrible idea.” When he plays the clip again, the words are so immediately discernible it’s hard to imagine how they couldn’t have been.

Sometimes the term hallucination confuses people (Seth wishes there were a better word): it might suggest that perception is arbitrary, or that things don’t exist. In fact, if our brains are working properly, we’re constantly updating our predictions based on feedback from our senses – which is why ordinary perception is a “controlled hallucination”, not a fever-dream. That said, Seth told me as we strolled across campus in search of a sandwich, he’s open to the idea that the physical world doesn’t exist in the manner we think it does. That’s a “question for a physicist, someone like Carlo Rovelli. Who knows what’s actually out there? But let’s assume things are out there and things exist,” he said. Reality, Seth believes, is the hallucination we can all agree on.

Some aspects of perception are more illusory than others. Our experience of ourselves, as having an enduring, stable identity over time, is a useful illusion. As is our perception of free will: we believe we are acting freely when we follow our own beliefs, goals or desires – but we can’t freely choose those beliefs, goals or desires. The purpose of consciousness, of all these hallucinations, is to keep us alive. When we die, it will be extinguished. Seth believes other animals are conscious, but doesn’t think artificial intelligence ever will be.

As for the “hard problem”, Seth believes that the better we understand our brains – the more precisely we can measure, manipulate and track consciousness – the less intractable the problem becomes. This theory doesn’t satisfy everyone: when I interviewed him for the New Statesman, Chalmers told me he disagreed that the hard problem can be solved this way – you still need to account for the mechanism by which objective matter produces subjective experiences. But he also emphasised their common ground: Seth’s approach of mapping conscious states on to brain states (identifying, for instance, which neurons correspond to “seeing red” or “thinking about dinner”) is “pretty much the same approach I would recommend”.

Seth spends a lot of time talking to people about the spiritual implications of his theories. They aren’t compatible with a literalist belief in a soul surviving death, but he sees a “deep compatibility” with many religious traditions: “You confront some of the same issues and ask some of the same questions,” he says. There are parallels between his work on the transient, constructed nature of the self and lessons in Hinduism and Buddhism. He meditates daily.

[See also: The Road to Conscious Machines is an accessible and highly readable history of artificial intelligence]

Seth grew up in rural Oxfordshire, where his mother worked as an English teacher, and his father, who emigrated from India in the 1950s, as a scientist at the Esso research centre. He was a bookish teenager, partly out of necessity; a skinny kid with thick glasses, he was a year younger than his classmates and not much good on the rugby or football pitch. (Like his father, Seth was an excellent badminton player, “but you can’t base your whole life around that in Oxfordshire”.) He studied natural sciences at Cambridge, focusing first on physics and later on experimental psychology.

A PhD in knowledge-based systems at Sussex, where he used artificial neural networks to model ecological and evolutionary processes, took him closer than psychology could to understanding how our brains work. His supervisor, Phil Husbands, told me that Seth was “probably the most focused PhD student I’ve ever had”. While most of his peers showed up to their first supervision with “an enthusiastic grin and something to take notes with”, Seth turned up with “dozens of pages of typed-up ideas and sketches of possible experiments”.

After Sussex, Seth moved to the Neurosciences Institute in California, where he worked with Gerald Edelman, the Nobel Prize-winning biologist who was instrumental in reviving consciousness science. He returned to Sussex in 2006, when the university offered him a lectureship, bringing some of his Californian habits with him: he surfs in Brighton, and last year swam in the sea close to his home daily.

After we’d eaten our sandwiches, Seth took me on a tour. When it was founded in 2010, the Sackler Centre was one of the world’s first multidisciplinary research groups devoted to the study of consciousness (there are now more than a dozen globally). Here, physicists, computer scientists, neuroscientists, psychologists and philosophers are researching some of humanity’s foundational mysteries: what is consciousness? Where does it come from? By better understanding this, they hope to develop new cures and treatments for neurological and psychiatric conditions such as coma, insomnia, depression and psychosis.

The Neurosciences Institute in San Diego had been so impressively futuristic that it was used in film sets, forming a backdrop to a 2000 sci-fi movie, The Cell. The Sackler Centre’s aesthetic is more “…British”, Seth observed. He made tea in a small kitchen with a large whiteboard covered with faded formulas and, scrawled over the top, the note: “What is the abomination in the blue cup?” Then he led me through a warren of narrow corridors to the unprepossessing offices where researchers are investigating all manner of quirks of the mind: why can hours sometimes disappear in the blink of an eye, and five minutes feel impossibly long? Why are some people more suggestible than others – to the extent that, when they see a spider crawling up someone else’s arm, they will also experience a tickling sensation? In one lab, researchers were using virtual reality to study “change blindness”: how much can you change about a person’s surroundings without them noticing?

Seth had lent his key fob to an intern, and, as he gave the tour, had to knock to be let in. On the office walls were optical illusions and old science posters, and the shelves were crammed with curiosities: mannequin heads, a Darth Vader figurine, half a dozen rubber hands. The atmosphere was laid-back and experimental: at one point, Seth picked up an electromagnet shaped like a pair of comedy spectacles – a transcranial magnetic stimulation (TMS) coil – which can be used to reduce activity in different parts of the brain. “Years ago, when we first got them, we had the whole idea that consciousness depended on the frontal and parietal network, so we just tried to shut the whole thing down using TMS on each other,” he said. “It didn’t work,” he added, replacing it with a shrug.

In the same room was a small booth that housed a hallucination machine. Inside the booth was a strobe light that pulses at the same frequency as our brain activity. The device, which induces vivid, colourful hallucinations, was based on a 1959 invention by the artist Brion Gysin, who believed his machine would supplant TV. Seth invited me to sit on a stool in front of the light with my eyes closed. I could not see the light; instead orange and green blobs appeared in my vision. They consolidated into rotating, pulsating kaleidoscopic shapes that grew more intricate, before dissolving into a white light so searing I would have closed my eyes were they not already shut. I felt close to panic, I told Seth afterwards. He looked crestfallen. My reaction put me in the minority – most people love the hallucinations. Seth finds the experience so “meditative” he has installed a stroboscopic light at home, which he uses for around half an hour a week.

This month, Seth and other researchers are working with the composer Jon Hopkins and the Turner Prize-winning artists Assemble on a project introducing the “Dreamachine” to members of the public and school children. Seth hopes to inspire a new generation of consciousness researchers and philosophers, and his team will be using a computer program to help participants recreate their hallucinations. Just as a glitching computer will sometimes give us clues as to how the machine works, the strobe light causes glitches that might deepen our understanding of how visual perception works. There is so much we still don’t know: when you and I see “red”, are we seeing the same colour?

Out of curiosity, I agreed to enter the booth once more, with a light that pulsed at a lower frequency. Seth suggested that, to stay calm, I describe the hallucinations to him as they appeared, and while I muttered about dancing green triangles morphing into rotating orange starbursts he said “Huh?” as though nothing were more interesting. After five minutes that felt like 30 seconds, the light stopped and so did my visions; it now felt strange to walk back to Seth’s office as though I hadn’t just returned from a journey to some strange outer galaxy.

When I first read Being You, I’d been struck by the loneliness of his vision. We are all, his work suggests, trapped in our self-created universes, internal worlds that are all we can ever know, and that will vanish in an instant. Walking out of the hallucination machine, I understood the optimism that drives his work, too: Seth’s belief that one day science might bridge the gulf between our own minds and those of others, so that we can see each other more clearly.

[See also: Into the Grey Zone: can one really be conscious while in a coma?]

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This article appears in the 02 Mar 2022 issue of the New Statesman, Hero of our Times