Category: Consciousness

The end of visual deprivation Aug 2, 2011, 7:34a - Consciousness It's the first day, morning, after opening my eyes after 7 days of visual deprivation. I opened my eyes last night, first in a dark room right after midnight, and then we lit a candle. The first thing that's very striking, even in the morning now, is that everything that's blue looks extremely BLUE. Either I forgot what blue looked ... more » No comments - Write 1st Comment Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Days 6 and 7 Aug 1, 2011, 12:51p - Consciousness [For background, see my first post on the experiment. This is a rough transcript of a dictation made on day 7.] It's T minus 11 hours. After talking to Sachin yesterday [day 6], he had a good idea to slowly introduce light back to me eyes, like starting with a candle or another single light source and then maybe ... more » No comments - Write 1st Comment Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Day 5 Jul 30, 2011, 11:31p - Consciousness [For background, see my first post on the experiment. This is a rough transcript of a dictation made on day 6.] Today was an interesting day. Very nice weather. I'm still pretty lethargic, I took a 2 and a half hour nap, but so did Becca so I'm not sure if it's due to my experiment. It was Jude's ... more » No comments - Write 1st Comment Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Day 4 Jul 29, 2011, 11:32p - Consciousness [For background, see my first post on the experiment. This is a rough transcript of a dictation made on day 5.] It's a beautiful day (referring to day 5). Right now I'm sitting in the sun, without a shirt on. It's quite nice. Boris (my tortoise) has emerged from his little borough. He didn't come out yesterday but he ... more » Read comments (2) - Comment Liz Dzeng - Aug 6, 2011, 5:43p Hey Nik! Wow, I'm so impressed that your doing this. It sounds incredibly hard with a huge amount of self discipline required. I could not even last an hour I bet if I tried. I've really enjoyed reading your posts which are so descriptive and introspective. You really should publish these findings in a scientific journal, so few experiments have been done on this. I'm really interested to read about your "unmasking"! Niniane - Aug 23, 2011, 1:14a Are there any more entries?? Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Day 3 Jul 28, 2011, 10:09p - Consciousness [For background see my first post on this experiment. This is a rough transcript of a dictation made on day 4.] I sort of just feel like I'm a puddle of mud. I sort of just feel like I would behave if I'm sick, cause I don't really do much and I just lie around all day. So it ... more » Read comments (1) - Comment Yu-li - Aug 6, 2011, 6:57a I like your introspective description. You really did something hard. I don't want to try that even though I wonder how it feels like. About construction of space, I think measure theory can be helpful. (http://en.wikipedia.org/wiki/Measure_theory) Even without visual information, it must be possible to construct mental space of things as we have information on spatial order of things. I think what matters is (mental) metric (http://en.wikipedia.org/wiki/Metric_%28mathematics%29). Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Day 2 Jul 27, 2011, 11:13p - Consciousness [For background see my first post about my blindness experiment. This post is a rough transcript of a dictation on day 3.] Yesterday I had a little bit of an adventure. I went around the block by myself. It's amazing how much I do not walk in a straight line. With cars going by on the street, it's amazing ... more » Read comments (5) - Comment Kanika - Aug 5, 2011, 4:40p I don't know if you did this already - bit about three years ago a movie came out- beautiful movie about the blind- called BLACK by Sanjay leela bansali staring amitabh.... I must watch it!!! Yu-li - Aug 5, 2011, 7:41p Interesting. Your experiment tells that normal sense of distance greatly depends on visual information.It must be specific to visual sense. Physically, other types of information are not very sensitive to distance I think (They are not linear. I mean, the strength of scent depends on both distance and quantity for example). I am sorry that my description is not very accurate. Good luck! Niniane - Aug 5, 2011, 9:05p This is an awesome story. I like all the details of how you're watching Teen Wolf, etc. It sounds domestic and pleasant. mom - Aug 12, 2011, 1:16p good reading your descriptions and findings son. Yes, the Indian movie 'Black' suggested by Kanika is wonderful and maybe you would be able to appriciate it. Netflix should have it. sakshi - Aug 24, 2011, 8:45p hmmm.. ive been out of the loop !!! just got back in.. another thumbs up for black !!! Name  Comment  Thanks! Your comment will be published in a few minutes. Visual deprivation: Day 1 Jul 26, 2011, 11:07p - Consciousness [All posts in this series have been backdated to the date they occurred. For background info on my visual deprivation experiment, see my first post on the topic. This post is a rough transcript of a dictation I made on day 2.] I started Monday night (last night) at midnight. Becca taped stretched-out cotton balls over my eyes, couple pieces ... more » Read comments (5) - Comment Nicky - Aug 5, 2011, 7:57a Did a desire to rip off the eye mask emerge after a few days? Did it just take longer than food deprivation or isolation? I am on the edge of my seat waiting for the next post! nikhil - Aug 5, 2011, 10:07a Nope, a desire to rip off the eyemask and open my eyes never emerged, certainly nothing like the desire to eat after food deprivation or the desire to breathe after air deprivation. Howard - Aug 5, 2011, 10:53a well, those are interesting comparisons because one could argue that the other two forms of deprivation you use for example are tied to very real needs of survival on a biological level. While food is a little different because given your survival school mean experiment you weren't lacking nutrition just variety and craving. With air deprivation, that's entirely different, no air = no life and your body starts to react involuntarily. so the one easy conclusion is that vision is not tied to survival instincts nikhil - Aug 5, 2011, 1:05p Howard, I completely agree. I also think it's interesting to think about the brain basis for each of these deprivations. Vision is believed to rely mostly on the outer parts of the brain (the cortex), whereas more basic body functions like breathing and perhaps even hunger lie deeper in the brain. Maybe it's these different brain locations that contribute to the different class of feelings that each type of deprivation generates. So maybe inner brain deprivations generate the intrinsic or visceral feeling to stop, while outer brain deprivations don't. Yu-li - Aug 5, 2011, 7:28p Hi, I've waited for your post! Your experiment is so interesting. Some ideas come to my mind. 1) You could feel sleepy because of conditioning. The sense of darkness might be associated with sleepiness. 2) You also could feel tired because of mental resource reallocation. (It's a hypothesis). I mean, in some sense, you had depended on visual feedback in order to control your movement. Now you have to decide your movement without some information, so you need to compensate the loss with other types of information. Your body and brain could have been working very hard subconsciously. 3) I think some portion of emotional stability(?) can be explained by decreased quantity of information. I mean, it might not be specific to visual sense. For example, if you cannot smell, you would feel quite indifferent to food. That's what I think. Good luck! Name  Comment  Thanks! Your comment will be published in a few minutes. My visual deprivation experiment Jul 15, 2011, 11:40a - Consciousness Starting tomorrow, I'm going to start a visual deprivation experiment on myself. For 1 week, I'm going to tape my eyes shut. I'm not going into the lab, and I'm certainly not going to be on the Interweb or reading email. I'm not sure exactly what I'll be doing - I'm guessing trying not to get hit by a car ... more » Read comments (6) - Comment neha - Jul 15, 2011, 9:51a I was going to ask you if you and Becca wanted to hang out soon. Perhaps the week after. Niniane - Jul 15, 2011, 8:28p Ok this is awesome. I want to hear how it is!!! Yu-li - Jul 16, 2011, 1:51p Sounds interesting! I would like to do the same experiment by myself, but I am too lazy... I think it is better to measure the effect as objective as possible. How about preparing a color chart so that you can compare the visual perception? Good luck! Dylan - Jul 16, 2011, 2:24p Good for you. I'm very curious to hear your findings after this. My non-informed guess is you will indeed make it a week, but will spend much of your time just sitting and listening to the radio. Retsina - Jul 18, 2011, 7:07a Very cool, Nikhil :) Mom - Jul 25, 2011, 2:53p Nik - You awesome but crazy kid, you must have begun your experiment by now. I know you will not be reading this blog until you restore your vision. You may look like a raccoon with white circles around your eyes...ha ha.Maybe a visit to the Braille institute will help you read faster and not get bored. Becca can convey my words if she is reading your blog to you. I look forward to discussing your observation with you...Be careful son. xoxox Name  Comment  Thanks! Your comment will be published in a few minutes. From physics to perception Jul 6, 2011, 10:10p - Consciousness I think the most interesting aspect of consciousness is the phenomenon of qualia, which is what it feels like to experience something (aka "subjective experience"). When philosophers talk about qualia, the canonical example of a quale is the "redness of red". Color perception in general amazes me. Specifically, I find it astonishing that my eyes and brain can take a ... more » Read comments (2) - Comment Namit - Jul 7, 2011, 11:45a Is it possible that color perception is a learned phenomena? Just as humans acquire language, which in turn alters their sensory intake, can the perception of color also be something that develops early on? I understand that linguists argue that language acquisition is facilitated by innate structures in our brain, that no doubt have evolved concurrently with our language systems. I am curious to know what color perception is like in babies or small children. Maybe they can experience a richer, more continuous spectrum of color than us as they have not yet learned the basic terms that both extend and limit our perception. The precise color resulting from light of arbitrary wavelengths may indeed be the result of shortcuts taken by our brain on the road to perception, like filling in a missing note of a chord. The spectrum is richer than that which our brains have the ability to perceive, and so it makes a close approximation based on what we're used to. This comment is much more broad than your above experiment, and one that is weighed heavily by speculation. Still curious though. Yu-li - Jul 9, 2011, 8:19p Hmmm. Qualia is a fascinating subject. I've loved to think about the mistery of qualia, but I have never approached it in physical terms like you. I've tried to discribe it more abstractly(mathematically). Reading your blog post, some ideas came to my mind. 1) I don't know whether the red I see is the red you see. However, red will be used in the real life to induce the same action from both of us. (This idea is kind of behavioralist or later-Wittgensteinish.) We generate the similar output to the same input whatever the internal state is. Data would show the similar pattern if we measure responce time to red letters on green background and red letters on pink background. As the same input generates the same(?) output, we can guess that we share the same/similar internal state(qualia). It cannot be directly proven that we have the same internal state for "red", but it can be indirectly supported. (Even though there are outliers(?) like synesthesia. Their color processing circuit might be different from it of ordinary people.) 2) Colar perception in babies or small children might be hard to study, because they cannot talk well. However, there are studies on blinded adults who had cornea transplanted. Since their color perception is not yet polluted(?) and they can describe what they experience, it is a better approach I think. 3) Taking the evolutionist approach, we can think that "The spectrum is richer than that which our brains have the ability to perceive", because it is not efficient use of mental resource for survival and reproduction to perceive the whole spectrum. That is what I think. Name  Comment  Thanks! Your comment will be published in a few minutes. A simple argument for the existence of the soul Jun 18, 2011, 9:55a - Consciousness (1) I am a conscious being with subjective experience of myself and the world around me. (2) No theory exists for how consciousness (specifically subjective experience or qualia) can arise purely from physical materials. If you assume (1) and (2) to be true, one logical result is that (3) We must live in a world that is not purely materialistic. ... more » Read comments (9) - Comment Gokul - Jun 18, 2011, 11:26a Hi Nikhil! How on earth is quest for consciousness related to quantum mechanics? like I hear these two things being linked many times.. What is it about? Is it just that we can travel to and fro in time only in our thoughts and memories? Jason - Jun 18, 2011, 7:51p Hey Nik. You may find this documentary interesting. I stumbled upon it recently on Netflix: http://www.quantumactivist.com/ Kate - Jun 19, 2011, 8:45a Nikhil, you crack me up. Who knew an argument for the existence for the soul could be so funny and stimulating? Good post. Here's my comment: while I'm not so familiar with the world of soul-existing arguments, but I think it's a little odd that one of the main tenets of your argument, (2), is that there is no pre-existing theory for X out there. "(2) No theory exists for how consciousness (specifically subjective experience or qualia) can arise purely from physical materials." Okay fine... but if there were such a theory (and you didn't like that theory), how would that affect your argument for the existence of the soul? I don't see that it would. Just sayin'... Keep poking worms. Neha - Jun 20, 2011, 10:14a (c) seems pretty right to me. We're still a long ways off from technology good enough to really get at neurons and what's going on in there! It seems incredibly premature to say that there is no correct theory of consciousness and will never be one. Give materialism a chance! nikhil - Jun 26, 2011, 1:50a To Gokul and Jason, on the topic of quantum mechanics and consciousness: One central argument against the existence of free will, which is a part of consciousness, is that if we live in a deterministic world governed by the basic rules of physics, there's no room for us to make a "choice". We don't decide what we do, the molecules just follow physical rules and everything is simply predetermined, without another source (free will) influencing things from the outside. So free will is just some sort of elaborate illusion constructed by our brain. Quantum mechanics changes our notion of determinism in 2 ways. First, fundamental particles become more "random" in that they're position in space seems best described with probabilities rather than definite locations. Second, the act of "observation" (which is not well-defined) forces the particles to adopt definite positions, so an external action seems capable of influencing the outcome of a physical system of particles. The interpretation that tries to connect consciousness with quantum mechanics builds on each of these ideas. First, because basic particles seem to move probabilistically and indeterministically, perhaps there is now room for free will, because everything isn't just particle-interaction destiny. Second, maybe free will acts as the "observer" and forces the random system of particles to adopt specific positions. This opens the door for free will as an external force that influences and determines reality. That said, I don't believe anything I wrote in the last paragraph. I think the beliefs around the connection between free will and quantum is 100% hopeful speculation on the part of various New Age thinkers and 0% scientifically supported. Roger Penrose, a famous mathematician/theoretical physicist, put forth the idea that quantum fluctuations in brain cells might support free will, but unfortunately there is zero evidence for this in neuroscience. But of course no one is doing quantum-level experiments in the brain, so it's not like this theory has been proven wrong. It just hasn't been tested, and it just seems highly unlikely given all that's known about how the brain works. More importantly from my perspective is that the theories above don't address the more basic part of consciousness, what's called the "hard problem" of qualia. Quantum doesn't deal with the question of how we have subjective experience of our world, something that most people intuitively believe is not the case for most other physical objects. What distinguishes our material composition from others' such that it supports qualia, so that we're not just robots behaving like we're alive but we're people actually experiencing life? I've heard no real theory for how qualia can be constructed in purely a materialistic manner, and I don't believe that such a theory can even exist. This is the main reason why I believe in the existence of the soul, or some non-materialist entity that interacts with the material to give materials new properties, such as qualia. nikhil - Jun 26, 2011, 2:09a To Kate, on the topic of materialistic theories of consciousness: If there was a real theory that explained how consciousness arises from material interactions, I would be super-intrigued. I would be satisfied with such a theory if it enabled me to distinguish conscious objects from nonconscious ones. So it could tell me whether my worms were conscious, or at least what information I'd need to know about my worms to determine whether they were conscious or not. Based on my original argument above, I would certainly have less logical reason to believe in the existence of the soul. However, I might still believe, due not to logic but certain life experiences (see http://nikhil.superfacts.org/archives/2008/11/why_i_believe_i.html). But regardless I'd be stoked. Yu-li - Jun 28, 2011, 8:09p Hi, thank you for another interesting post. As for me, I am an agnostic, but I believe in free will (I often say that "I am determined to believe in free will.") I desperately(?) "want" to believe in non-materialistic soul, but I cannot erase my doubts. I should say I'm still in confusion. There is a need to distinguish "high-level consciousness" and "lower-level consciousness". Consciousness requires computation, and as you know materialistic theories do exist for computation (like how neural signals are generated and processed). The theories can explain at least lower-level consciousness, and I think worms have very low level consciousness at least. I would like to quote Marvin Minsky : "we'll show that you can build a mind from many little parts, each mindless by itself. I'll call "Society of Mind" this scheme in which each mind is made of many smaller processes." I think it makes some sense even though I do not like its strong materialistic scent... His approach implies hierarchy of consciousness, and low level consciousness can be materialistic at least. For high level consciousness (like decision making or construction of theory of mind), I feel a lot of confusion. Emotion is the hardest and most important part, because emotion gives "meaning" to computation. I doubt whether we can perfectly figure out what materialistic processes can generate emotion. However, there are so many other systems(human beings, other animals...) that can generate emotion, and it means emotional systems can be "replicated" in this world. It could imply emotion is also materialistic. I do not believe that there is a clear line between material and mind though (I'm an agnostic). That is what I think. Harpoon - Jul 15, 2011, 7:18p Hey Nikhil, great topic. I'm pretty much in agreement with your points. From what I've intuited and read (or rather haven't read) we can't even express theories about consciousness and there's no certainty we ever will. I like Noam Chomsky's succinct comment, "what mind-body problem?" Check out this talk he gave: http://youtu.be/yJp1-Od67-U Starts out slow, but he draws some very compelling connections. However this is a follow up to an even better talk he gave previously I believe is called "Linguistics and Philosophy". I've done some thought experiments on whether consciousness can be divorced from brain. Most of them have gone awry, because I wasn't willing to kill my brain to try it out. The biggest practical joke by consciousness on humans may be the obvious question of what governs the material world. So we could go in the other direction, and ask what I think is a much harder question: what individuates humans from one another, and from other beings, so that they come to call things "consciousness". Which I know sounds similar to the Gaia concept dullblade - Aug 30, 2011, 5:53p I envy your intelligence and your systematic approach to this age-old question. Also you must be a person of great feeling and intuition to arrive at the conclusion that you do; that we do possess "consciousness". Do you believe you can resolve your philosophical question with purely analytical or logical means? Our consciousness is self-evident. That you question it's origin demonstrates the poverty of vision of modern man. We, who have grown up in the age of science, are reluctant to embrace any acknowlegment of our utter incapacity to reach a conclusion about the true mystery and terror of life. You cannot get there from here,( our logic and rational mindset). Godspend to your quest. May you find a way to explain how the divine is manifest in every material part of our wondrous world. Name  Comment  Thanks! Your comment will be published in a few minutes. To Be Conscious in a Body, Frozen May 16, 2009, 11:21a - Consciousness It's hard to tell if a thing is conscious. You know, if there is something that it feels like to be that thing. I know it feels like something to be a person, and I think it doesn't feel like anything to be a shoe (unless perhaps I've been smoking some salvia), or to be a dead person. But what ... more » Read comments (13) - Comment Tom Stocky - May 19, 2009, 6:26a Wow, ingenious is right -- thanks for sharing this. omar - May 19, 2009, 9:41p dear god. this is ingenious, but i am just thinking about this person who is locked in. i think they are likely totally insane. or almost. how could you not be, with no ability to communicate with the world? when i read the diving bell book, at one point i was reading on the bart. it made me feel so claustrophobic that i almost threw up and had to get off the bart and breathe. just reading your blog post is making me nauseous. hope you are well! Ruggero - Aug 14, 2009, 3:02p Is a worm conscious? nikhil - Aug 17, 2009, 7:22a short answer: i don't know whether a worm (e.g. C. elegans) is conscious. long answer: hmm, what a damn tricky question. there are a few issues. first, it seems that it is in principle impossible to know if something other than yourself is truly conscious. if you define consciousness to be the phenomenon of having a subjective experience of the world (which is how i use the word most of the time), it seems plausible that another creature could act as if it were conscious even though it had no subjective experience. it would answer your questions, behave "normally", and even say "yeah, i'm conscious", but there may in fact be nothing that it is like to be that creature; in other words, the creature may act as if it has subjective experience without ever having any - it would fake it. and in principle, it seems impossible to know when something might be faking it. this applies equally to other humans as to other organisms, such as the worm C. elegans. in general, though, when it comes to humans, I seem to make a sort of similarity argument: i'm conscious, and other humans seem to be a lot like me, so they're probably also conscious. so in practice we make assumptions that seem to be consistent with common sense, but in principle confirmation of consciousness in another creature seems unknowable. second, let's just forget the first problem and say that yes, there exists a behavior that can only exist if a creature is conscious. so if the creature can act in a certain way, then i conclude that it is conscious. which behavior would I use as the test for consciousness? in practice, being able to respond sensibly to questions seems like a nice test, but as in the article above, verbal response seems sufficient but not necessary. also, it doesn't extend very well beyond humans, as we seem to be the only species that has a highly-expressive language (at the very least, we don't have good ways of communicating with other creatures in their own language, if they have one). intuitively, i think my dog is conscious, yet I communicate with her in extremely simple ways. and i can imagine that even if i couldn't communicate at all with my dog, she might still be conscious. my conclusion that my dog is conscious is based largely on empathy and similarity of response - she responds to things (e.g. hunger, anger, treats) in a way that i also respond to those things. so now on to worms. i have nearly no empathy with worms, and there lives are so different than mine that it's really hard to tell based on intuition alone whether they're conscious. but you can do things in worms that are easier to do than in any other organism: you can identify genes, molecules, cells, and groups of cells that are required for certain behaviors. so if consciousness is due to some physical process (a big assumption), studying worms might be a good way to find pieces involved in that physical process - assuming, of course, that they are conscious (to some degree) to begin with. i guess this is a very long-winded way of saying that i don't know whether a worm is conscious. there is a specific type of learning that is correlated with awareness in humans (a variant of Pavlovian classical conditioning), and i'm in the process of testing to see whether the worms can do this type of learning. if they can, it would be one small piece of speculative evidence that worms (specifically C. elegans) might be conscious. my hope is that over time we'll discover more behavioral tests that are correlated with consciousness in humans, and that worms could then also be tested. if i accumulate enough pieces of speculative data, the whole argument might become a lot more convincing. that's one strategy, at least. Ruggero - Oct 15, 2009, 12:53p thanks for the very accurate answer. let's assume that C. elegans is conscious (which i believe is true). is a bacterium conscious? is the fact that a system possesses a neural net that makes it conscious? or isn't just their reaction to a behavioural test? if the reaction makes it conscious then also a bacterium is conscious, since it replies to external stimuli as any other creature. aren't neural nets only there because of the size of the systems and therefore the necessity of a faster communication between parts than that achievable chemically? nikhil - Oct 18, 2009, 3:26p i don't think that just because an organism has a neural net it's also conscious. like i said, i believe you need to find a behavior or some other observable that correlates well with awareness or consciousness. the presence of a neural net could be an example of such an observable, but given that there are many examples of nonconscious states in humans who have neural nets (e.g. vegetative states, dream-less sleep), i don't believe a neural net is sufficient. a neural net may be necessary, as there don't exist any examples of conscious creatures without neural nets, but that is less helpful in identifying those creatures which are conscious. (as an aside: i prefer using the word "organism" or "creature" over the word "system", as i think "system" masks the complexity found in biology that is not found in standard engineered "systems") i want to be clear - i don't believe that just any behavioral response is sufficient to show that a creature is conscious. people talk in their sleep and sleepwalk all the time, ostensibly without any consciousness at that moment (or at least very low levels). it's actually pretty interesting to record yourself sleeping - i got a nightvision camera that can do this, and i do all sorts of strange things in my sleep. one night i woke up holding a light bulb in my hand, with no memory of how it got there. the light bulb had been lying on my nightstand, so i just put it back, but it was a bit bizarre... what i'm working with so far is a specific behavior called trace conditioning. i think i've blogged about it before; it's a specific type of pavlovian conditioning that involves specific time delays between the paired stimuli. i may blog about it in more detail at a later point. right now i'm working under the assumption that if an organism can trace condition, than this is sufficient for consciousness. this assumption is based on the fact that trace conditioning is well-correlated with awareness in humans, while other forms of conditioning are not. neither a bacterium nor a paramecium (a larger single-celled creature) are capable of trace conditioning (though no one has ever tried, as far as i know). no one has shown that c. elegans can trace condition. getting trace conditioning working in c. elegans is actually my main research project, and if i can show that they trace condition, then that's a tiny shred of evidence that it may be conscious. for your last question, size does not necessitate the presence of a neural net / nervous system. paramecium are much larger than bacteria (~300 microns at its longest length, comparable to baby C. elegans larvae), and they are single cells without any neurons. they do have ion channels and they conduct electric currents, which only goes to show that you don't need a neural net to conduct currents. even plant cells have been shown to conduct currents, so many cells likely have this property. neurons are generally defined by shape (a cell body with at least one process reaching away from it) rather than by their ability to conduct. hope this is helpful (and not too confusing). Sanjana - Mar 15, 2010, 9:42p Along with saliva, irises should change a significant amount (contract/widen) in response to what someone imagines or sees, right? How accurate do you think an experiment on "iris contractions" in a person's reaction to certain images would be? (Or do you think recording saliva pH would be more accurate than videotaping someone's irises...?) nikhil - Mar 23, 2010, 11:31a i'm not familiar with any experiments that discuss pupil dilations due to imagined seeing. is there a specific paper you're thinking of, or are you just assuming this to be true? it's an idea that should be really easy to test. measuring saliva pH was used in the study above, but i don't remember if they did the positive control: can a non-comatose person control the pH of their saliva to answer questions? i'm not sure (though i assume yes). if a non-comatose person can also control pupil dilations in response to questions, it seems reasonable to test this on comatose patients too (as you suggest). Sanjana - Mar 23, 2010, 5:36p I have read of non-comatose people seeing specific pictures and having their saliva pH change accordingly. How can a comatose person's saliva pH/pupil dilations change if they are unresponsive? If the neurons controlling the muscles are "dead," isn't the person only able to breathe? (If a comatose person's nociceptors/non-nociceptors don't work, does that mean that they feel absolutely no pain either?) nikhil - Mar 31, 2010, 9:31p A comatose person may not be able to control some muscles (such as their arms and legs), but may be able to control other body functions (such as their eyes or saliva pH). It probably comes down to exactly why they are "comatose", and whether they have any residual function. I think you can probably be comatose for many reasons, not just because your neurons are dead. For example, maybe a connection to the muscles is missing, and the neuron needs to regrow the connection. But I think this is still very much an open research question, with little known (as far as I know). Same goes for pain. As an example, there are stories of people who say that they experience pain while under anesthesia. They claim that they were actually aware during the surgery, and that they could feel, but they couldn't speak or respond in any way. It's complicated stuff, very little of which is actually understood. Gokul Rajan - Nov 18, 2010, 7:19a Hey Nikhil! Is not consciousness a defining feature of all living organisms in their normal living state? Well, atleast thats what we learn in our high school biology! In that sense even C. elegans or for that matter any other worm should also be conscious! It is just that we dont know how these different organisms exhibit their conscious behavior... isn't it? or am i utterly wrong?? nikhil - Nov 19, 2010, 10:12a Clearly some living organisms go through different states of consciousness (e.g. awake vs. asleep). So even if you're alive, if you're asleep all the time I don't think that that minimal level of consciousness (if any) would be enough for me to say that the person has conscious experience. So no, I don't think consciousness is a defining feature of all living things. Also, the definition for life is hard at its boundaries: is a virus alive? It only has DNA, and depends on other organisms to reproduce. It's so simple that some believe that it's not even fair to call it alive. So if we're not sure whether it's alive, how do we know if it's consciouss? More interestingly, does a virus (or bacterium) have anything that it feels like to be that virus (or bacterium)? Maybe it's so difficult for us to imagine that we might say no. Or maybe all living things have consciousness, so then a virus must too? Hard to say. Gokul Rajan - Nov 20, 2010, 8:29a Well, a virus i think cannot be considered as living.. but yeah some do consider it as living.. its just a mass of protein with a little genetic matter.. so we cannot search for consciousness in a virus... but i mean all organisms which have nerve cells starting from phylum coelenterata or platyhelminthes i guess should be conscious! but as you said having neural networks may not necessarily indicate consciousness.. but then why is it so? And yeah.. this is a very interesting thing that when we sleep we are in the subconscious state! And i feel sleep especially the REM stage should be one of the hottest area of research! Is this area really given such high importance?? I did read about your own sleep experiments with the night vision camera! That was really interesting! I'll try it myself! But investigating genes associated with consciousness is a far fetched idea but equally interesting also! All the best bro!! I'll follow your work and hopefully one day you will come up with the genetic basis of consciousness!! Name  Comment  Thanks! Your comment will be published in a few minutes. Brave New Mescaline Jun 14, 2008, 3:14p - Consciousness I just finished reading Aldous Huxley's double-book, "The Doors of Perception" and "Heaven and Hell." It was a welcome break from all the academic papers I've been reading lately. Basically, the book is about Huxley's experiments with mescaline (also known as peyote) in the 1950s. Mescaline is a drug that is known to cause vibrant hallucinations for up to 10 ... more » No comments - Write 1st Comment Name  Comment  Thanks! Your comment will be published in a few minutes.

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