Return to site

Summary of Dr Anil K Seth views on consciousness

  • David Chalmers’s influential distinction, inherited from Descartes, between the ‘easy problem’ and the ‘hard problem’.
    • The ‘easy problem’ is to understand how the brain (and body) gives rise to perception, cognition, learning and behaviour.
    • The ‘hard’ problem is to understand why and how any of this should be associated with consciousness at all: why aren’t we just robots, or philosophical zombies, without any inner universe?
  • It’s tempting to think that solving the easy problem (whatever this might mean) would get us nowhere in solving the hard problem, leaving the brain basis of consciousness a total mystery.
  • But there is an alternative, which I like to call the real problem: how to account for the various properties of consciousness in terms of biological mechanisms;
    • without pretending it doesn’t exist (easy problem)
    • and without worrying too much about explaining its existence in the first place (hard problem).
  • A good starting point is to distinguish between conscious level, conscious content, and conscious self.
    • Conscious level has to do with being conscious at all – the difference between being in a dreamless sleep (or under general anaesthesia) and being vividly awake and aware.
    • Conscious contents are what populate your conscious experiences when you are conscious – the sights, sounds, smells, emotions, thoughts and beliefs that make up your inner universe.
      • And among these conscious contents is the specific experience of being you. This is conscious self, and is probably the aspect of consciousness that we cling to most tightly.
  • Conscious level
    • conscious level is not the same as wakefulness.
      • When you dream, you have conscious experiences even though you’re asleep.
      • And in some pathological cases, such as the vegetative state (sometimes called ‘wakeful unawareness’), you can be altogether without consciousness, but still go through cycles of sleep and waking.
    • So what underlies being conscious specifically, as opposed to just being awake?
      • We know it’s not just the number of neurons involved. The cerebellum (the so-called ‘little brain’ hanging off the back of the cortex) has about four times as many neurons as the rest of the brain, but seems barely involved in maintaining conscious level.
      • It’s not even the overall level of neural activity – your brain is almost as active during dreamless sleep as it is during conscious wakefulness.
      • Rather, consciousness seems to depend on how different parts of the brain speak to each other, in specific ways.
  • Consciousness is :
    • informative in the sense that every experience is different from every other experience you have ever had, or ever could have
    • integrated in the sense that every conscious experience appears as a unified scene. We do not experience colours separately from their shapes, nor objects independently of their background
  • Tononi, who pioneered this approach, argues that consciousness simply is integrated information.
    • This is an intriguing and powerful proposal, but it comes at the cost of admitting that consciousness could be present everywhere and in everything, a philosophical view known as panpsychism.
    • The additional mathematical contortions needed also mean that, in practice, integrated information becomes impossible to measure for any real complex system.
    • This is an instructive example of how targeting the hard problem, rather than the real problem, can slow down or even stop experimental progress.
  • When we are conscious, we are conscious of something
  • In the 1990s, Francis Crick and Christof Koch defined a ‘neural correlates of consciousness’ NCC as ‘the minimal set of neuronal events and mechanisms jointly sufficient for a specific conscious percept’.
  • In the 19th century, the German polymath Hermann von Helmholtz proposed that the brain is a prediction machine, and that what we see, hear and feel are nothing more than the brain’s best guesses about the causes of its sensory inputs.
    • Think of it like this. The brain is locked inside a bony skull. All it receives are ambiguous and noisy sensory signals that are only indirectly related to objects in the world.
    • Perception must therefore be a process of inference, in which indeterminate sensory signals are combined with prior expectations or ‘beliefs’ about the way the world is, to form the brain’s optimal hypotheses of the causes of these sensory signals – of coffee cups, computers and clouds. What we see is the brain’s ‘best guess’ of what’s out there.
    • people consciously see what they expect, rather than what violates their expectations
    • The classical view of perception is that the brain processes sensory information in a bottom-up or ‘outside-in’ direction: sensory signals enter through receptors (for example, the retina) and then progress deeper into the brain, with each stage recruiting increasingly sophisticated and abstract processing. In this view, the perceptual ‘heavy-lifting’ is done by these bottom-up connections.
    • The Helmholtzian view inverts this framework, proposing that signals flowing into the brain from the outside world convey only prediction errors – the differences between what the brain expects and what it receives.
      • Perceptual content is carried by perceptual predictions flowing in the opposite (top-down) direction, from deep inside the brain out towards the sensory surfaces. Perception involves the minimisation of prediction error simultaneously across many levels of processing within the brain’s sensory systems, by continuously updating the brain’s predictions.
      • In this view, which is often called ‘predictive coding’ or ‘predictive processing’, perception is a controlled hallucination, in which the brain’s hypotheses are continually reined in by sensory signals arriving from the world and the body.
  • A number of experiments are now indicating that consciousness depends more on perceptual predictions (what the brain expects), than on prediction errors (the differences between what the brain expects and what it receives ).
    • In 2001, Alvaro Pascual-Leone and Vincent Walsh at Harvard Medical School asked people to report the perceived direction of movement of clouds of drifting dots (so-called ‘random dot kinematograms’). They used TMS to specifically interrupt top-down signalling across the visual cortex, and they found that this abolished conscious perception of the motion, even though bottom-up signals were left intact.
    • "we’ve found that people consciously see what they expect, rather than what violates their expectations."
  • Of the many distinctive experiences within our inner universes, one is very special. This is the experience of being you
    • conscious selfhood is also best understood as a complex construction generated by the brain.
      • There is the bodily self, which is the experience of being a body and of having a particular body. 
        • cf the famous ‘rubber-hand illusion’
      • There is the perspectival self, which is the experience of perceiving the world from a particular first-person point of view.
      • The volitional self involves experiences of intention and of agency – of urges to do this or that, and of being the causes of things that happen.
      • At higher levels, we encounter narrative and social selves. The narrative self is where the ‘I’ comes in, as the experience of being a continuous and distinctive person over time, built from a rich set of autobiographical memories.
      • And the social self is that aspect of self-experience that is refracted through the perceived minds of others, shaped by our unique social milieu.
    • In daily life, it can be hard to differentiate these dimensions of selfhood. We move through the world as seemingly unified wholes, our experience of bodily self seamlessly integrated with our memories from the past, and with our experiences of volition and agency.
    • But introspection can be a poor guide. Many experiments and neuropsychological case studies tell a different story, one in which the brain actively and continuously generates and coordinates these diverse aspects of self-experience.
    • bodily senses include :
      •  proprioception, which signals the body’s configuration in space,
      • and interoception, which involves a raft of inputs that convey information from inside the body, such as blood pressure, gastric tension, heartbeat and so on
    • "This virtual hand was programmed to flash gently red, either in time or out of time with their heartbeat. We predicted that people would experience a greater sense of identity with the virtual hand when it was pulsing synchronously with their heartbeat, and this is just what we found"
  • It now seems to me that fundamental aspects of our experiences of conscious selfhood might depend on control-oriented predictive perception of our messy physiology, of our animal blood and guts. We are conscious selves because we too are beast machines – self-sustaining flesh-bags that care about their own persistence.
Also, don't miss his amazing TED Talk, 6 millions views :
All Posts

Almost done…

We just sent you an email. Please click the link in the email to confirm your subscription!