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Let's start with a definition
Aug 10, 2012, 10:05p - Consciousness

My main intellectual interest is to understand how the brain creates consciousness. When I tell this to people, they usually respond with "What do you mean by 'consciousness'? How do you define it?"

Human consciousness is certainly complex, but I think of it as being composed of 3 smaller parts, arranged in a hierarchy. The most primitive part of human consciousness is subjective experience, or the fact that it feels like something to exist and interact with the world. When I handle a hot frying pan, I feel the heat in my hand. Though I experience this feeling of heat, the frying pan, the over-easy eggs, the stove, and the fire itself do not. Not only do I have the capacity for experience, each of my feelings can feel very different. It feels different to touch something cold, or wet, or rough. Emotions are also a kind of experience. But the details of each experience are unimportant for our definition. The main point is this: the most fundamental aspect of human consciousness is the ability to have subjective experiences. I'll call this foundational component of consciousness perception.

The second part of human consciousness is the sense of self. This builds on top of perception quite simply. To have a sense of self is to classify my perceptions as those that arise directly from the outside world and those that come from my own body. I can almost imagine a creature with perception but without any sense of self. This creature is constantly experiencing: there's the light from the moon, there's the wind cooling the earth, there's some pain caused by the dog ravishing that piece of meat over there. What the creature doesn't know is that the meat over there is actually its own leg. The world is just a bunch of experiences for the creature, all on the "outside". When the creature evolves a sense of self, it now realizes that the pain is its own, that its emotions are its own. If I can barely imagine such a perceptive self-less creature, I cannot at all imagine the inverse, a perception-less self-ful creature. Without perception, how can this creature even individuate itself from the rest of space around it? Doesn't it have to feel something first? So I think our sense of self builds on top of our capacity for perception.

The third and final part of human consciousness is free will. Not only do I have a self separate from the rest, I can control what this self does. There is much debate over whether free will actually exists - given our current scientific understanding of the world and its materialistic, deterministic nature, there isn't any space for true free will in science. But I will ignore this debate for now. Suffice to say that free will is the pinnacle of consciousness, and builds on top of a sense of self and perception.

It is in this way that I define consciousness. Human consciousness consists of 3 parts: perception, a sense of self, and free will. I think it's an open question as to whether non-humans have all or only some of these parts of consciousness. I will argue in later posts that I think creatures perhaps as simple as fruit flies and the nematode C. elegans, which I study, have some aspects of conciousness. Certainly objects and non-living things show no evidence of having any of these parts of consciousness.

Now that we have a working definition, the challenge is this: How can a materialistic world produce any of these aspects of consciousness? I'll simplify this a bit by cutting out the more sophisticated aspects of consciousness, the self and free will. So how can a materialistic world produce experience of any kind? In other words, how do some configurations of matter (e.g. our brains) create experience, while other configurations of matter (e.g. chairs) do not? This question is a bit too hard, akin to asking how positive and negative charges attract. Ultimately they just do, so still this is not the right question. A better question is this: What are the configurations of matter that create perception, and how do they differ from configurations that do not? OK, now we're getting somewhere. Might it be possible to disect those objects (e.g. brains) to find those sub-parts that enable perception, and then compare those parts to other parts of the brain that do not? I think this might be a reasonable plan.

This is question that is motivating me to study neuroscience instead of doing other things with my time here.

I think this question might be answerable, if not in my lifetime in someone's lifetime thereafter. It is a question rooted in philosophy but manifested in experimental terms. This is the question I'm going to devote the next several blog posts to. Hopefully by writing these thoughts down I can clarify my own thinking, and by responding to comments I can clarify yours as well.

Consciousness is the essence of what we are. If we seek to understand ourselves, we must first understand the physical basis of consciousness.

Read comments (6) - Comment

TomN - Aug 12, 2012, 12:03a

If you haven't read "Second Person, Present Tense" by Daryl Gregory, I highly recommend this SF short story.

You can find a copy via the Internet Archive:

The author's notes are an interesting post-read:

It is just Science Fiction and it's a few years old now, but you might enjoy it.

nikhil - Aug 12, 2012, 10:49a
That's a neat story Tom. Thanks for that.

Another way to think of the 3 facets of consciousness is:
* Step 1 = Perception : "Stuff is happening."
* Step 2 = Self : "Some of the stuff that is happening is happening to me."
* Step 3 = Free will : "I have control over the some of the stuff that is happening to me."

Raja - Aug 13, 2012, 12:14p
"If we seek to understand ourselves, we must first understand the physical basis of consciousness."

Is this true? Might it be enough to have a working, descriptive understanding of how consciousness manifests itself, i.e. how we humans tend to interpret and relate to our notion of consciousness? Is it necessary to get answers to its physical underpinnings in order to live a meaningful life?

Put another way, how would having answers to the questions you are posing change the way you live or interpret your existence? It's fine if you just happen to be interested in thinking about and trying to find answers to those questions, but it's a much stronger claim to say that getting answers to these questions is somehow "important."

Somewhat related question (via the late philosopher Richard Rorty): Can you hypothesize a potential answer to the questions you've posed that would be satisfying and coherent? For most questions we ask about the world, it's usually pretty easy to give an example of a coherent answer even before doing any investigation. It's then possible to do research and test hypotheses that are based on our a priori "guesses".

It's not entirely clear what those testable hypotheses would even look like with respect to the most difficult questions surrounding consciousness (e.g. free will), but I am curious to hear what you think and what the current take on that problem is within the neuroscience community.

nikhil - Aug 14, 2012, 6:56a
Good to hear from you Raja!

Alright, let's start at the beginning. In general, I think either I haven't been clear or you've misunderstood me. My quote:

"If we seek to understand ourselves, we must first understand the physical basis of consciousness."

I am definitely no trying to imply that it is necessary to answer the question of consciousness to live a meaningful life. Clearly no one has a satisfactory answer to this question but clearly loads of people live meaningful lives (or have meaningful aspects to the lives they live). I think we're debating 2 kinds of "understanding" - the first one (which I think you're talking about) is at the descriptive level. Take another phenomenon, let's say flying. When humans wanted to understand flying, it was totally reasonable to begin by surveying birds and floaters in the wind and other things that naturally flew. Describe them, describe their body plan and anatomy, their colors, and any other descriptive attribute - when they flew, for how long, from where to where, etc. With this compendium of knowledge, it's possible to predict whether new objects would fly or not (inference), and also to build something that flew (perhaps some of those fast-flapping lightweight bird-looking toys fall into this category). But I would say that this level of understanding remained superficial, even though the total bulk of knowledge was huge. To really understand flight more generally, I think you had to understand certain concepts, such as lift and how differential air pressure supports flight in the shape of wings. This second kind of understanding follows from the first, but the first alone is not satisfactory in my opinion, though necessary for getting to the second. This analogy can also be applied to the field of medicine and how a molecular understanding of diseases is a much less superficial understanding than a symptom-level kind of understanding. This is the epistemology of reductionism.

This quote is definitely not meant to have much existential power - think of it more as "if I want to get past the superficial and really get a better flavor of consciousness, I've got to start thinking about the mechanisms that underly it. I have to physically dissect it." As far as we can tell consciousness should have a physical basis, so other kinds of dissections (e.g. psychological, metaphysical, behavioral) may be interesting and helpful, but they won't get at the heart of the matter, so to speak.

This is not meant to be depressing or have any emotional content. It's just meant to be a statement of fact.

I only think the basis of consciousness is "important" if you care about consciousness - most people I talk to don't think about it at all. So for them it isn't important. But if you happen to be one of the few who are interested, I think it's important in the sense that if you want to be a good doctor, understanding the molecular basis of your patients' ailments is important. It's not the whole story and many other pieces also need to be there, but without it there's a huge gap in the work.

On to your "what would a potential answer even look like?" question. Again I guess I wasn't clear enough in my writing. For the question, "How does certain parts of the brain create consciousness", I don't think there is a possible answer, and I agree with you. I likened that to asking "How do positive and negative charges attract?" or "How does mass generate gravity?" These are questions about the properties of objects, properties which ultimately form a sort of ground truth. Even if I answer those questions I could always ask how the answers exist and just move the question one level down, forever. At some point I just have to accept that there are objects with specific properties, and go from there.

So the motivating question is clearly "How does the brain create consciousness?" but I'm willing to accept that consciousness is just a property of the brain. It's like saying that objects which have the properties X, Y and Z will also have the property of consciousness. What I'm now interested in, and what I think is scientifically tractable, is to figure out what the properties X, Y and Z are. Ideally, these properties would be both necessary and sufficient for consciousness. We know that some parts of the brain clearly play more important roles in consciousness than other parts, and I will write about one example in a later post. Why does part A of the brain have a role in consciousness while part does not? What makes these 2 parts, though sitting right next to each other, different in relation to consciousness? Is it what other parts they're functionally connected to? The way in which they're connected? Posed this way, the question becomes one of comparison, and comparing things is what science is all about (experiment vs. control).

I hope this long-ish comment clarifies. I'm also primarily focused on the question of perception, not of self or free will, so my comments above are directed at that aspect of consciousness.

The goal now is to find those neural differences that make the difference between conscious experiences and unconscious ones.

Andy L - Aug 30, 2012, 11:45a
Great post! Looking forward to see where you are taking this!

Gokul - Oct 14, 2012, 11:05a
Another wonderful post! Looking forward for the rest in the consciousness series!

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