On consciousness

Today we discuss progress on the understanding of consciousness with Dr. Larissa Albantakis, PhD in computational neuroscience at Universitat Pompeu Fabra and Associate Scientist at the Wisconsin Institute for Sleep and Consciousness at the University of Wisconsin – Madison.

David: What is consciousness?

Larissa: Consciousness is subjective experience — ‘what it is like’, for example, to perceive a scene, to endure pain, to entertain a thought or to reflect on the experience itself. When consciousness fades, as it does in dreamless sleep, from the intrinsic perspective of the experiencing subject, the entire world vanishes (from Tononi et al. 2016 Nat Neuro).

As you see, there is no one sentence definition of consciousness and even in the field of consciousness science people do not agree, as there is confusion between consciousness itself and its associated functions. But consciousness, as discussed in philosophy is about phenomenology, not function. A nice case to see the dissociation is dreaming. You are conscious while you are dreaming, because you have experiences, even though you are largely disconnected from the world and you might not remember them shortly after awakening.

David: Has progress been made on the nature of consciousness? Are there theories of consciousness?

Larissa: There are several "neuroscientific" theories of consciousness. The most prominent are Global Neuronal Workspace Theory, Higher order thought theory, recurrent processing theory, and integrated information theory (IIT). Some count predictive processing accounts, but those are more theories about brain processing and not consciousness per se. Of these theories, however, only IIT is actually concerned with phenomenal experience, rather than the functional consequences of consciousness. In other words, most of the scientific theories of consciousness do not ask about the nature of consciousness, only its functions. By contrast, IIT starts by asking what the essential properties of consciousness are and then argues that any physical system that forms a substrate of consciousness should also have these properties. Again, I would refer to Tononi et al. 2016 Nat Neuro if you want to learn more about this. I would say that scientists are slowly moving toward the idea of "taking phenomenology seriously". Historically, phenomenology was a taboo topic as many thought it could not be studied objectively. The science of consciousness then got revived in the late 1990s by the idea that one can study neural correlates of consciousness and set aside questions about its nature for the moment. This approach was quite successful but we are reaching its limits and so more people are asking about the neural mechanisms giving rise to phenomenal experience, not just correlates or markers of consciousness. Anil Seth's book on consciousness is to be recommended here. We also had a paper outlining a path for an objective science of the subjective (https://pubmed.ncbi.nlm.nih.gov/34667639/)

In philosophy there is much discussion about the metaphysical nature of consciousness, where the most prominent positions are physicalism, idealism, illusionism, and panpsychism. Since you are a physicist I should add that there are still researchers and philosophers pursuing the idea that consciousness has to do with quantum mechanics, but that idea is not very popular as quantum effects do not seem to play any role in cognition.

David: How does causality inform the study of consciousness?

Larissa: As mentioned above, in neuroscience researchers are beginning to ask about the neural mechanisms underlying phenomenal experience. Sometimes this is phrased as "necessary and sufficient conditions" though there may be issues with this take due to multiple realizability etc. There is also some work in physics about the role of the observer, but this is not directly about consciousness usually. Then there is the question about the causal closure of the physical and whether consciousness thus has to be epiphenomenal.

Finally, in IIT causation forms the basis for consciousness. The idea is that consciousness arises from the causal interactions of the system's parts, which have to fulfill a set of essential properties (e.g., being informative and maximally integrated). IIT postulates an identity between the current experience of a system and the cause-effect structure specified by the system in its current state.

David: Is it reasonable to talk about degrees of consciousness?

Larissa: In healthy human beings, consciousness seems rather binary. We have it when we are awake and we lose it in dream-less sleep, or under anesthesia. But there are conditions, such as delirium, or under psychedelics where it is conceivable that there are changes in the "vividness" of our experiences. There are also patients with brain disorders, who are classified as "minimally conscious", who may have brain damage in parts of their cerebral cortex. In these cases it seems reasonable to talk about degrees of consciousness. It also makes intuitive sense across species. Nevertheless, there is some debate about this question (Bayne et al. 2016; http://www.sciencedirect.com/science/article/pii/S136466131630002X)

David: Is consciousness emergent?

Larissa: That's a tricky question, first of all because "emergent" is a very controversial term and people mean very different things when they use it. There is an obvious sense in which consciousness is emergent and that is that the spatio-temporal scale at which our conscious experiences "run" seem to involve neurons or groups of neurons (rather than atoms or quarks etc.) and time scales of tens of milliseconds. Accordingly, the physical substrate of our consciousness is not to be found at the micro level of physics. However, emergent is often paired or contrasted with epiphenomenal, or associated with some dynamically emergent pattern that is observer-dependent. Consciousness is observer-independent, so it cannot be emergent in the mere sense of "level of description". There has to be an observer-independent reason why consciousness runs at the specific spatio-temporal scale that it runs at. In that sense, consciousness is not like a flock of birds. It is real, meaning it exists in a fundamental way. David: What does the near future look like for consciousness studies? Larissa: I will refer again to Anil Seth's book and also to our paper on studying the subjective in objective terms (Ellia et al. 2021). I hope that there will be a shift from research on neural correlates to identifying the mechanisms underlying phenomenal experience. More detailed neuroimaging tools will certainly help here. Also, the field of consciousness science is looking more towards its theories, how they differ, how they are aligned, and whether there are experiments to distinguish between them. See Melloni et al. 2021 (https://www.sciencemag.org/lookup/doi/10.1126/science.abj3259).

David: Thank you Professor!