The following report written by Shreyas Gadge gives a detailed review of a book talk that was given by Neuroscientist Anil Seth (Professor of Cognitive and Computational Neuroscience at the University of Sussex) at India Science Festival 2022.

Consciousness, according to Professor Seth is any kind of subjective experience, be it pleasure, pain, emotion, or intention; they all form an aspect of consciousness, which is different from intelligence or language. A more philosophical definition by Thomas Nagel reads, ‘An organism has conscious mental states if and only if there is something it is like to be that organism.’ For example, we humans can’t experience the inner universe of a bat but for a bat, it feels like something to be that bat; which is the same for all other living beings.

The understanding of consciousness is challenging within our wider picture of the natural world, which is always put in terms of a physicalist description of matter and its interactions. How these interactions form consciousness is one of the outstanding problems in science and philosophy. This problem has been crystallized by philosophers like David Chalmers and Rene Descartes, termed as the ‘hard problem’ of consciousness. Chalmers in his quote talks about how experiences arise from a physical basis but it seems objectively unreasonable why such physical processing gives rise to a rich inner life at all. Chalmers contrasted this hard problem with the easy problem of how brain mechanisms give rise to complex functions and behaviors. The latter is challenging but the intuition behind calling it easy is that there is no conceptual mystery that is associated with the pristinely untouched problem of deciphering consciousness which leads to the belief in dualism of the physical universe and the universe of consciousness as two different modes and how they interact forms the part of the hard problem. Thinking of this problem in a very black and white sense gives rise to many potential responses.

One, that is getting academically popular is the idea of panpsychism which states that consciousness is fundamental and ubiquitous. This obviates the hard problem because if consciousness is built into the fabric of the universe from the ground up, we don’t need to explain how it comes to be. Basically, it means that there is nothing special about
consciousness as a scientific and philosophical problem and thereby this is not really an answer as it can’t be tested or doesn’t generate any testable hypotheses. It is articulated by philosophers like Keith Frankish and Daniel Dennet. The next position is illusionism which states that consciousness doesn’t really exist, at least not in ways we normally think of. Professor Seth describes this position as akin to a powerful medicine that is needed in specific amounts to regulate our naive intuitions about consciousness.

Professor Seth, in his book ‘Being You: A New Science Consciousness’ explores the real problem by focusing on how mechanisms and processes in the brain and body explain, predict and control properties of consciousness both functional, that is, what we can do in virtue of being conscious and critically phenomenological. It’s neither the hard problem nor the easy problem as we aren’t looking at how and why consciousness is a part of the universe nor are we sweeping its mystery away under the carpet. The real problem is inherited from ‘Neurophenomenology’ pioneered by people like Francisco Varela and Evan Thompson; which is nothing but understanding phenomenological properties through neural mechanisms. The principle of Vitalism in the 19th century looked at life beyond the remits of Physics and Chemistry and with biologists starting to explain the properties of living beings like metabolism and reproduction, the hard problem or the mystery of consciousness gradually dissolved with an appeal to understand its properties in terms of mechanisms.

“The intrinsic difference between understanding a living system and understanding consciousness is the subjectivity of a conscious experience with respect to the objective recording of the data of a living system.”

Professor Seth divulges the understanding into three dimensions of consciousness; the conscious level, which is the difference between being in a dreamless sleep or under anesthesia and being awake or aware; the conscious content, which is being conscious of something (people, places, etc.); and the conscious self, which is the experience of being an individual in the world.

We can try to comprehend these dimensions through the idea that the brain is a prediction machine. The cave of Plato forms an allegorical explanation to this idea as the shadows cast by the firelight in the cave were treated as the real world by the prisoners. Updating this allegory in modern times, we understand perception as the brain’s best guess of the causes of ambiguous sensory inputs by taking into account its prior expectations. Take the example of Adelson’s checker shadow illusion that makes the squares of a checkerboard lying on a shadow appear to be darker compared to the ones not lying on the shadow, even though they are essentially the same shade. This can be quantitatively understood by Bayes’ theorem which updates a prior belief using the new data (or likelihood) and gives us an updated belief, or posterior, mathematically. With the onset of the 19th and 20th centuries, scientists like Hermann Von Helmholtz talks about perception as unconscious inference.

Basically, when we start looking at perception in terms of neural mechanisms, we see that perceptions are predictive hypotheses made by the brain where the prediction errors are passed bottom-up and predictions of sensory signals are passed top-down the neural trajectories. The brain continuously calculates the difference between expectations and sensory inputs to update expectations by minimizing the error. The posterior is thereby the best guess made by the brain. The hypothesis is that we consciously perceive this continuously evolving brain-based best guess calibrated by sensory data of the real world in an active form. Predictive processing is although not a theory of consciousness but gives sufficient ingredients to explain the properties of phenomenology in terms of underlying mechanisms which is close to the real problem analysis. Various sensory and computational techniques such as continuous flash suppression and running backward the neural networks for object recognition; could then be used to understand the nature of our conscious experiences such as those of unusual perception like seeing faces in the clouds, hallucinations, or uncontrolled perceptions, and so on. By doing this, we can understand more about normal perception too, which Professor Seth describes as a controlled hallucination.

The larger claim is that this theory applies to all the aspects of our experiences of the world and also to the experience of being a self. This gives an intuition that the self is not just perceiving the world and acting upon it but the self is a perception too created in the same way as the perception of the world. Even the experience of embodiment of yourself is more than just having a body but also being a body associated with moods and emotions. On similar lines, interoceptive predictions, that is, of the senses inside the body are more focused on control and regulation rather than action and hence they underpin embodied experience as the goal of the body is not just to enact but to also keep itself alive and feeling.