Physical correlates of consciousness

Question

The term neural correlates of consciousness is well established (~ 277,000 Google results, one Wikipedia article), but I'd like to ask for more general physical correlates of consciousness (~ 6,000 Google results, one Scott Aaronson talk) which are at the same time more general and more specific.

The impression that every novice must have is that the only candidate of a physical correlate of consciousness is some kind of (averaged) electromagnetic field: it's all about depolarization, action potentials, neural firing, ...

But there are other physical quantities that might be considered (together with their averaged spatio-temporal distributions over the volume of the brain):

• more general or abstract forms of energy (as the prototypical extensive property)

• some kind of enthalpy (as another extensive property)

• temperature or some kind of (as a prototypical intensive property)

• some spatio-temporal density of other extensive quantities (as another type of intensive property)

Edit: Which specific (physical) quantities (and their spatio-temporal patterns) have actually been considered as (physical) correlates of consciousness?

Answer 1

Information, information that exists in the neural processes, is probably the physical quantity that correlates perfectly with consciousness.

Consciousness is a very complex and dynamic entity: you’re conscious of many things that have a lot of complicated, fine details and that always change and change rapidly (in milliseconds), such as the consciousness of the vision and sound of the environment around you. Energy, enthalpy, and temperature do not have this complexity and dynamicity: they are all about the same throughout the whole brain and do not change significantly in milliseconds. Most importantly, however, is the fact that the nervous system has evolved to get information from the outside world, process the information, and send command (information) to the body’s effectors to respond appropriately to survive. The nervous system hasn’t evolved to deal with the energy, enthalpy, or temperature, per se: these thing by themselves do not mean anything to the nervous system. However, if these things somehow affect the being, it is the duty of the nervous system to extract information from them to get the characteristics of their effects to respond appropriately. So, functionally, the nervous system deals principally with information only, and because consciousness (the kind that exists in us) is a function in the nervous system, consciousness is very likely to be some kind of information in the nervous system.

Chalmers [1,2] noted that “there is a direct isomorphism between certain physically embodied information spaces and certain phenomenal (or experiential) information spaces” and formed a hypothesis that “Information (or at least some information) has two basic aspects, a physical aspect and a phenomenal aspect. … Experience arises by virtue of its status as one aspect of information, when the other aspect is found embodied in physical processing … We might say that phenomenal properties are the internal aspect of information”. This is the concept of the double-aspect theory of information. However, Chalmers thought that the double-aspect theory of information was extremely speculative and also underdetermined and did not develop it into a full-fledged theory.

Others do, however. The Integrated Information Theory (ITT) [3-5] asserts that consciousness is a kind of integrated information in the nervous system. To be exact, by this theory, a conscious experience is a maximally irreducible conceptual structure (MICS), which corresponds to a local maximum of integrated conceptual information (or a local maximum of Φ or Φmax). It uses these quantities to predict which system is or is not conscious fairly successfully in varieties of cases, such as not being conscious during sleeps or generalized seizures or in the cerebellum. It also proposes that there may be some kind of consciousness, the protoconsciousness, in plants and predicts that digital computers, no matter how functionally equivalent to us they are, can never have consciousness. It also provides mathematical formulations to calculate Φ. However, it does not give rationales of why such MICS, which corresponds to a local maximum of Φ, should become a phenomenal conscious experience or why phenomenality should occur in MICS. Phenomenality and phenomenal consciousness just occur in MICS.

The Basic Theory of the Mind [6] asserts that consciousness is information in some specific forms. According to this theory, information in some specific forms (such as reentrant signaling states in some specific forms) means phenomenal consciousness in the neural process language; so, when these kinds of information are read and interpreted (by the process of reentrant signaling) by the consciousness neural process, phenomenal consciousness (not non-phenomenal consciousness) naturally and unavoidably occur in the consciousness neural process. Therefore, the most crucial factor whether any information is or can be phenomenal consciousness is that its form must be in some specific form that means phenomenal consciousness when interpreted by the consciousness neural processes – that is, the specificity, not the complexity, of forms of information is the determining factor. Interestingly, according to this theory, as information is inherent in (not emergent from) the neural signaling, consciousness naturally exists in some forms of reentrant signaling states. This answers the hard problem of consciousness of why and how non-material phenomenal consciousness can and should arise from material neural processes. No new physical entity emerges to be consciousness, consciousness is already there naturally.

There are many other interesting theories about neural correlates of consciousness, some involves neural resonance states, some involves Electromagnetic Information (Cemi) Field, some involves quantum vibration of neural microtubules, etc., but I don’t think I can review them all here. There are several good reviews on the net, such as ref 7,8, and 9. If you’re interested, please examine them.

References.

1. Chalmers DJ. Facing up to the problem of consciousness. J Conscious Stud. 1995;2(3):200-219.

2. Chalmers DJ. Moving forward on the problem of consciousness. J Conscious Stud. 1997;4(1):3-46.

3. Tononi G. An information integration theory of consciousness. BMC Neurosci 2004,5:42. DOI: 10.1186/1471-2202-5-42.

4. Tononi G. Integrated information theory of consciousness: An updated account. Arch Ital Biol. 2012 Jun-Sep;150(2-3):56-90. DOI: 10.4449/aib.v149i5.1388.

5. Oizumi M, Albantakis L, Tononi G. From the phenomenology to the mechanisms of consciousness: Integrated Information Theory 3.0. PLoS Comput Biol. 2014 May;10(5):e1003588. DOI: 10.1371/journal.pcbi.1003588.

6. Ukachoke C. The Basic Theory of the Mind. 1st ed. Bangkok, Thailand; Charansanitwong Printing Co. 2018.

7. Van Gulick R. Consciousness. In: Zalta EN, editor. The Stanford Encyclopedia of Philosophy (Summer 2017 Edition). Retrieved 2017 Sep 8 from

8. De Sousa A. Towards an integrative theory of consciousness: Part 1 (neurobiological and cognitive models). Mens Sana Monogr. 2013 Jan-Dec;11(1):100–150.

9. Seth A. Model of consciousness. Scholarpedia. 2007;2(1):1328.

Answer 2

It is not totally clear what the question is (perhaps edit), but I take it to be whether there are other candidate physical correlates of consciousness. An obvious candidate would be behavioral correlates of consciousness, such as people talking about how amazing it is that there are qualia. In the Scott Aaronson talk you link to above, slide 13 mentions this briefly. Relatedly, there have been proposals for variants of Turing Tests to detect consciousness (https://blogs.scientificamerican.com/observations/is-anyone-home-a-way-to-find-out-if-ai-has-become-self-aware/).