Being You: A New Science of Consciousness

by Anil Seth

The many different elements of my conscious experience right now – computers and coffee cups, as well as the sound of a door closing in the hallway and my thoughts about what to write next – seem tied together in an inescapable and funda...

In a maximally information-rich brain, all neurons would behave independently, firing randomly as if they were completely disconnected. In such a brain, measures of algorithmic complexity, like LZW complexity, would score very high. But this brain – with lots of information but no integration – would not support any conscious states. At the other extreme, a maximally ordered brain would have all neurons doing exactly the same thing, perhaps firing in lockstep together, somewhat like what happens during global epileptic seizures. Algorithmic complexity here would be very low. This brain would also lack consciousness, but for a different reason: lots of integration, no information. A fit-for-purpose measure of conscious level should therefore track not information itself, but rather how information and integration are

jointly expressed.

Yet a fundamental question still remains. Is consciousness more like temperature – reducible to and identifiable with a basic property of the physical (or informational) universe? Or is it more like life, a constellation of many different properties, each with its own explanation in terms of underlying mechanisms?

The approaches to measuring consciousness we’ve met up to now take their cue from the temperature story, but my intuition is that in the end they may fit better with the analogy from life. For me, ‘integration’ and ‘information’ are general properties of most – perhaps all – conscious experiences. But this doesn’t mean that consciousness is integrated information, in the same way that temperature is mean molecular kinetic energy.

Bauby (1997). You might think that being locked-in is a fate worse than death, but while some people in this condition do find life intolerable, a surprising proportion report a reasonable quality of life (Rousseau et al., 2015). This underscores the dangers of assuming how things are on the inside from how they appear on the outside.

In a follow-up study, led by Lionel Barnett, we found that the psychedelic state involves significant reductions in ‘information flow’ between regions of the cortex. This again

speaks to a loss of perceptual structure in the psychedelic state.

Reflective insight is preserved in the rare ‘lucid dreaming’ state, in which dreamers are aware that they are dreaming and can voluntarily direct their behaviour. In a remarkable recent study, researchers were able to communicate with people during lucid dreams by using their eye movements as a channel, much like the locked-in patients described earlier. These dreamers were able to correctly answer simple math problems and various yes/no questions.

‘integrated information theory’ of consciousness

This is Tononi’s brainchild, and more so than any other neuroscientifically motivated theory, it tackles the hard problem of consciousness head on. IIT says that subjective experience is a property of patterns of cause and effect, that information is as real as mass or energy, and that even atoms may be a little bit conscious.

exemplifies the analogy between consciousness and temperature. According to IIT consciousness simply is integrated information. In making this case, the theory upends deeply held intuitions about how mind and matter relate, and about how consciousness is woven into the fabric of the universe.

The easiest way to think about Φ is that it measures how much a system is ‘more than the sum’ of its parts, in terms of information.

system is conscious to the extent that its whole generates more information than its parts.

proposal about how mechanistic properties of a system account for properties of phenomenology.

Second, there must be more information when considering the system as a whole than when dividing it into its parts (its individual neurons, or groups of neurons) and considering all the parts separately. This is integration,

every conscious experience is both informative and integrated, inhabiting the complex middle ground between order and disorder.

Besides the axioms of integration and information, IIT proposes three others: that consciousness exists, that it is composed of many elements, and that it is exclusive to a particular spatiotemporal scale (Tononi et al., 2016). The philosopher Tim Bayne has critiqued IIT on the basis that its proposed axioms, particularly the final one regarding ‘exclusion’, may not in fact be self-evidently true (Bayne, 2018).

Perceptions do not come from the bottom up or the outside in, they come primarily from the

top down, or the inside out.

What we experience is built from the brain’s predictions, or ‘best guesses’, about the ...

Helmholtz proposed

the idea of perception as a process of ‘unconscious inference’.

The contents of perception, he argued, are not given by sensory signals themselves but have to be inferred by combining these signals with the brain’s e...

In calling this process unconscious, Helmholtz understood that we are not aware of the mechanisms by which perceptual infe...

‘predictive coding’ and ‘predictive processing’.

perception as controlled hallucination,

First, the brain is constantly making predictions about the causes of its sensory signals, predictions which cascade in a top-down direction through the brain’s perceptual hierarchies (the grey arrows in the image opposite). If you happen to be looking at a coffee cup, your visual cortex will be formulating predictions about the causes of the sensory signals that originate from this coffee cup. Second, sensory signals – which stream into the brain from the bottom up, or outside in – keep these perceptual predictions tied in useful ways to their causes: in this case, a coffee cup. These signals serve as prediction errors registering the difference between what the brain expects and what it gets at every level of processing.

By adjusting top-down predictions so as to suppress bottom-up prediction errors,

the brain’s perceptual best guesses maintain their grip on their causes in the world. In this view, perception happens through a continual pr...

The third and most important ingredient in the controlled hallucination view is the claim that perceptual experience – in this case the subjective experience of ‘seeing a coffee cup’ – is determined by the content of the (top-down) predictions, and not by the (bottom-up) sensory signals. We never experience sensory

signals themselves, we only ever experience interpretations of them.

But what we actually perceive is a top-down, inside-out neuronal fantasy that is reined in by reality, not a transparent window onto whatever that reality may be.

On the top-down view of perception, this sharp distinction becomes a matter of degree. Both ‘normal’ perception and ‘abnormal’ hallucination involve internally generated predictions about the causes of sensory inputs, and both share a core set of mechanisms in the brain. The difference is that in ‘normal’ perception, what we perceive is tied to – controlled by – causes in the world, whereas in the case of hallucination our perceptions

have, to some extent, lost their grip on these causes. When we hallucinate, our perceptual predictions are not properly updated in light of prediction errors.

If perception is controlled hallucination, then – equally – hallucination can be thought of as uncontrolled perception. They are different, but to ask where to draw the line is like a...

Let’s take the controlled hallucination theory for a spin by asking what it means to perceptually experience colour. Our visual system, amazing though it is, only responds to a tiny slice of the full electromagnetic spectrum, nestled in between the lows of infra-red and the highs of ultra-violet. Every colour that we perceive, indeed every part of the totality of each of our visual worlds, is based on this thin slice of reality.

Just

knowing this is enough to tell us that perceptual experience cannot be a comprehensive representation of an external objective world. It is ...

This means that colour is not a definite property of things-in-themselves. Rather, colour is a useful device that evolution has hit upon so that the brain can recognise and keep track of objects in changing lighting

conditions.

The entirety of perceptual experience is a neuronal fantasy that remains yoked to the world through a continuous making and remaking of perceptual best guesses, of controlled hallucinations.

You could even say that we’re all hallucinating all the time. It’s just that when we agree about our hallucinations, that’s what we call reality.

What’s remarkable about this example is that, when you look at the original two-tone image now, the sensory signals arriving at your eyes haven’t changed at all from the first time you saw it. All that’s changed are your brain’s predictions about the causes of this sensory data, and this changes what you consciously

see.

having a strong prediction about the causes of sensory signals changes – enriches – perceptual experience.

perception to be a generative, creative act; a proactive, context-laden interpretation of, and

engagement with, sensory signals.

we never experience the world ‘as it is’.

The controlled hallucination of our perceptual world has been designed by evolution to enhance our survival prospects, not to be a transparent window onto an external reality, a window that anyway makes no conceptual sense.