How Princeton neuroscientist Michael Graziano uncovers the magic of the human consciousness

The celebrated scientist talks attention, awareness, and the reception to his work

January 02, 2020
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I think therefore I am, said René Descartes in his 1637 Discourse on Method. What could be more foundational to our basic worldview? Although our senses are fallible, there’s an unshakable I at the centre of it that witnesses what the senses report, fallible or otherwise.

When neuroscientists have previously studied consciousness, they’ve typically assumed this preexisting, conscious, self-aware I as a starting point, and accepted that the challenge for science is to explain how something lumpy and biological like a brain can produce our first person experiences. But science is often called upon to provide objective third-person accounts of phenomena. So, when scientists try to explore “consciousness,” they are routinely accused of trespassing by those in the humanities or spiritual traditions. Their attempts seem doomed from the start, because consciousness is understood to be part of a domain off limits to science.

Rethinking Consciousness, by the Princeton neuroscientist Michael Graziano, offers an entirely different framing of the problem. Rather than explain how the physical brain somehow manifests the aura of conscious experience, the question becomes: why are we systematically misled, by our own brain, into thinking that consciousness has nonphysical, experiential, properties that mere physical objects don’t have?

Attention vs awareness

Graziano’s answer to this question is the attention schema theory. The crux of the theory is that it distinguishes between attention and awareness. They sound similar but attention here relates to the things your brain is focusing on at any given time. A torrent of information comes in from the external senses and internal reports, but only some of it is attended to closely at the expense of other less important information. Attention is a completely physical and non-controversial computational process.

Awareness, on the other hand, is synonymous with what we typically mean by consciousness. It’s a subjective feeling, a quality of experience; it has properties that are unlike anything else in the known universe. It seems imbued with a magical spirit or essence.

Graziano’s theory posits that awareness is actually a kind of crude model, or schema, of attention. We have evolved to not only have attention, a staggeringly rich computational process, but also to attribute to attention some nonphysical properties—like the magical spirit or essence we feel conscious life possesses—simply because it was a low-bandwidth way for the brain to keep a running summary of what attention is focused on. Crucially, the attention schema also helps us model the attention of others, including following their gaze, anticipating what their attention is focused on and treating them like beings animated by the same inner life as ourselves. Such skills were vital in our evolutionary history as gregarious primates.

When we’re asked to describe what it’s like to be conscious of things, we look inside ourselves and find awareness, which in Graziano’s words is “an ethereal thing like plasma, vaguely localisable to space inside us, an experience that is intangible, a feeling that has no physicality.” At least that’s how the brain’s caricature of attention, the attention schema, represents it.

Magic of the brain

This might be understood as saying that consciousness isn’t real or isn’t as wonderful as it seems. But Rethinking Consciousness puts forward the case that conscious awareness certainly is real, albeit some of its apparently magical properties are unreal and are artefacts of how the brain represents our own and others’ attention. Even still, this does seem to render the most personal, indeed spiritual, qualities of our inner life as no more than a byproduct of evolution’s kludgy solution to a computational problem: how to usefully model the unwieldy flood of data involved in focused attention and to model the same in others.

Graziano points out, however, that the attention schema actually needs to be misleading, or at least a simplification, otherwise we couldn’t have evolved consciousness at all. “If it were more literally accurate it would take more compute time and it would not function correctly. It’s beautifully balanced, so let’s not devalue it. But let’s understand it’s a model: a simplified proxy for something much more complicated.”

His lab at Princeton is working to find more evidence for the attention schema and to pinpoint which brain regions are responsible. A feature of the theory, which has earned respect among many scientists and artificial intelligence researchers, is that it makes testable predictions and should therefore be easily falsified if untrue.

Indeed, if the attention schema turns out to be generated by a well-understood network in the brain, then it should be possible in the near future to program a computer to have an attention schema. Such a computer would then, when prompted, report that its own inner state has nonphysical or magical properties.

A man or a machine?

Would this impress anyone? We believe other people when they say they’re conscious. But a computer telling us it is conscious doesn't seem especially compelling, even if it’s running software to emulate our own kind of awareness.

It may be that only a first person kind of evidence would convince people, especially philosophers, who might argue that we actually don’t know if other people are conscious and can only be certain of our own experience. Sceptics of Graziano’s approach will have to wait until brain stimulation techniques become sufficiently fine-tuned.

If the network responsible for running the attention schema could be inhibited and disinhibited at will, a person could visit a lab and have brain stimulation toggle them back and forth between having awareness and not having it, while still being otherwise awake and alert. What would that feel like?

Graziano and his colleagues have already conducted experiments heading in that direction, using transcranial magnetic stimulus. This technique harmlessly reduces the functioning of a selected area in the brain. By targeting the area thought to be responsible for attributing awareness to others, one of their experiments demonstrated reduced awareness of some objects in the subject’s own visual field, unbeknownst to them, as though they had an enlarged blindspot in their vision. In other words, partial inhibition of the machinery in the brain that models the awareness of others also reduced the subject’s own awareness. This is suggestive of the existence of something like the attention schema.

When I asked what a total inhibition of the part of the brain responsible for awareness would feel like—currently technically infeasible—Graziano said it “might lead to a weird gap, almost like when people suffer a very small seizure and come back a moment later. You might not notice anything is wrong, since the machinery for noticing is being affected.”

Ironically, even a first person experience of the glitchy and brain-based nature of consciousness still would not make it apparent, because we cannot be conscious of that which we’re not conscious of. A person would have to be shown a video of themselves losing and regaining consciousness in order to believe that it had happened via brain stimulation alone. Perhaps even more subtle stimulation techniques could knock out some flavours of awareness and not others, thereby resulting in a kind of awareness denuded of certain properties. Perhaps some of the magical sheen would be taken off conscious experience and one could be in a state of awareness closer to that of the human-like machines we aim one day to build.

Ultimately, the scientist’s attempt at a third person account of what constitutes first person awareness will have to do so without invoking the I in "I think, therefore I am." “People start out with the base assumption that there is something in us which is nonphysical,” says Graziano, adding that, “As soon as you start with that assumption you’re stuck, because you can’t explain it.”

Graziano admitted that whenever he gives a talk about his theory, a minority of the audience get the theory while the rest are utterly unconvinced. This may be not so much a problem of people failing to understand the theory as failing to see it. Rethinking Consciousness is a very accessible work of science popularisation. There’s limited jargon and Graziano guides the reader with numerous pop culture references and helpful analogies.

But it acts as a magic eye test. One group of readers may not see what the big deal is or just think it’s not answering the problem at hand; another group will squint and the profundity of this theory will lurch into view. Speaking as someone who used to be in one group but is now in the other—dare I say I “get it”—it’s quite a shift in perspective. In fact, it’s partly about rethinking what perspective is.

Rethinking Consciousness by Michael Graziano is published by W.W. Norton