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Mind & Psychology

The best books on Consciousness

recommended by David Carmel

NYU Research Scientist explains his passion for the study of consciousness. Recommends a range of books and articles to further our understanding of this subject that bridges science and philosophy

David Carmel

David Carmel is a research scientist at the Carrasco Lab, part of New York University’s Department of Psychology and Center for Neural Science.  His area of research is Consciousness, with an emphasis on visual awareness.

David Carmel at Carrasco

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David Carmel

David Carmel is a research scientist at the Carrasco Lab, part of New York University’s Department of Psychology and Center for Neural Science.  His area of research is Consciousness, with an emphasis on visual awareness.

David Carmel at Carrasco

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Your first choice, Introducing Consciousness

by David Papineau and Howard Selina, is presumably trying to make a very complex topic accessible by presenting it using graphic art?

Yes, it’s part of the Introducing… series that presents various topics in graphic form, a bit like a comic book. What I liked about this one is that it takes a very complex issue and shows that you do not need to be a great philosopher, or have a very deep understanding of the science, to understand why it’s a complex issue and what the fundamental questions we’re dealing with are. And the truth is that with consciousness we’re still at the point of raising the interesting questions, as philosophers have done for the last 2,000 years, rather than at the interesting, complex, answers stage. Despite being highly approachable, this book is a serious piece of work that gives a great overview of past and current thinking about consciousness, especially from the philosophical perspective. Most books or articles will look at the issue of consciousness from a different angle, and I’ve tried to balance that out in my choices. This particular book was written by a professor of philosophy, David Papineau, in conjunction with an illustrator. So it’s mostly about the philosophy of mind, with particular reference to consciousness, and while it mentions science here and there, that’s really not the main focus: where it mentions the science, this is done to describe potential methodologies with which to address the philosophical questions that have been raised.

Whereas you would say there is actually more to the science than that?

Not necessarily. I’m a scientist, and my own approach to these questions is scientific. But I got interested in consciousness because of the philosophical issues. What is consciousness? How can we possibly understand it? One of the frustrating things for scientists who deal with consciousness is that nowadays we have lots of great methodologies to look at the brain and at complex forms of behaviour. But we still lack a conceptual framework with which we could recognise an answer if it came along. The answer might be all around us: we may just not see it yet.

But wouldn’t pinpointing consciousness be the same as pinpointing the soul?

That’s one of the main issues: is there a soul that is separate from the brain or from brain activity? Most scientists nowadays, including me, don’t believe there is. The biggest question in consciousness, what David Chalmers has called the ‘hard problem,’ is how can brain activity, the activity of something physical like neurons, give rise to something that to us is mental, that feels like something? It isn’t just about information processing: ‘Oh here’s the visual input, this is what it means, therefore it should induce this kind of action.’ Computers can do that, but we really don’t ascribe a soul to them. So what is it about brain activity that makes red look specifically like red? Or pain actually hurt – rather than just serving as a signal to say “avoid doing this in the future”? How does brain activity lead to things feeling like something? How does brain activity make us creatures with consciousness, with self-awareness, with a mental life? That’s still a philosophical question, and here’s why: we know a lot more about brain activity than we did several years ago. But say, for example, that I can now associate visual experience with a particular area of the brain, meaning I now know that whatever it is that gives rise to my visual experience happens in a particular location of the brain. How does that help me understand how that that activity leads to red looking like red? It really doesn’t. It just takes the question one step further back. Now I know that activity here leads to that. That still doesn’t tell me why that particular brain activity leads to things feeling or looking a certain away…

Do you think you’ll find the answer in your lifetime?

Well I, personally, won’t! Others might…When I got into this originally, when I started graduate school, I thought: ‘Yes! Here’s an interesting question, give me a few years and I’ll solve it.’ I no longer think that. Science works incrementally; we will know a lot more than we know now by the end of my lifetime – we already know a lot more than we knew when I started graduate school in 2002. But all we know are details, we’re still looking for that conceptual framework – and that would require a revolution in thinking, and there’s no way of knowing when those might occur.

So the first article you’ve chosen is ‘Detecting Awareness in the Vegetative State’ by Adrian Owen et al, published in Science in 2006, and two critiques of it,

(available here and here along with the author’s response)

which is right at the forefront of research, but only one page long and fairly accessible to the lay person. Why is it on your list?

One of the big questions in consciousness research is how do we tell when someone – or something – is conscious? There are a range of opinions, from ‘anything alive is conscious including bacteria’ through to people who think only “high” animals are conscious: so dogs and cats may be conscious, but spiders aren’t. And there are people who say that only people are conscious – or go even further and say, ‘Hang on, the only person each of us has access to the consciousness of, is ourselves. We actually don’t know if anyone but ourselves is conscious.’ We may act and behave as if all other people are conscious – and we’re hardwired to naturally believe so – but we don’t actually have direct access to that.

So how do you know whether someone is conscious or not? And specifically, what if you look at someone who is non-responsive, and is diagnosed as being in a vegetative state? Can you be certain that they are indeed unconscious, that they don’t have an inner mental life, that they don’t understand what’s going on around them? Or even if for some reason their sensory input is cut off, and they don’t know what’s going on around them, maybe they’re still in there screaming ‘I’m alive!’ So this is one thing newer techniques might be able to answer. These researchers took a woman who had been in a vegetative state since being in a car accident and put her in an MRI scanner. They gave her two different kinds of instructions that involved mental imagery – which they say is something that only conscious people can do: they asked her to imagine either playing tennis or walking through her home. And they got her to respond: her brain responded in the same way that normal healthy people’s brains responded, showing a different pattern of activation to each type of imagery. So their conclusion was that she was conscious.

And what were the criticisms of the paper?

No one disputes that the paper itself is fascinating. The question is, does this brain activity really indicate that she’s conscious? When we first read it in our journal club after it appeared, everyone said, couldn’t this just be evidence of how much the brain can do without consciousness? No one can say this isn’t actually unconscious brain activity. One of the limitations of functional MRI is that it’s correlational. You can’t infer from the brain activity itself that that activity is causing a behaviour  – it’s just happening at the same time. Which means, in this case, that it could be happening without actually indicating any consciousness. So two commentaries were published, from the many criticisms that were made of the researchers’ claim. One was based on the fact that we already know a lot of semantic brain activity can be evoked by stimuli that we’re not aware of. For example, if you expose people to written words, subliminally, too fast to notice what was written, there will still be brain activity related to the meaning of those words. This is a different situation, of course, but it could very well be that brain activity is evoked by certain words and doesn’t necessarily indicate consciousness. So that’s what one commentary said: that maybe these are just areas of the brain that respond to the word tennis, or home or room. The other criticism was based on logic. The fact that we know that certain mental thoughts lead to certain brain activity does not imply the opposite, that certain brain activity means that you’re having certain thoughts. The researchers took conscious people and when they told them to think about tennis or walk through the rooms of their house, these were the areas that lit up. They concluded that if these areas light up, this means that someone is thinking about playing tennis or walking through the rooms of their house. That’s a logical fallacy, it’s like saying if all cucumbers are green, then everything green is a cucumber.

So what was the upshot?

That particular group of researchers, their work is fantastic: they do really interesting research. And just because you can’t get to a conclusive answer, doesn’t mean it wasn’t worthwhile. One of their responses was to say, OK, in order to infer from certain brain activity that it’s conscious, you have to be able to associate with some kind of decision-making. So the answer is we give the person several choices: if they’re conscious they can choose one thing and not the other. So they found more vegetative patients whose brains responded in this way, and they taught them to associate thinking about tennis or walking through the rooms of their house, with the answers ‘yes’ and ‘no’ to specific questions, questions that had nothing to do with tennis or walking through the rooms in their house – like, ‘Is your name so-and-so?’ That’s a newer paper that appeared only this year.

And that worked?

With some patients. Again, one of the things you learn about science when you’re actually doing it is that it’s messy. You never get a really clear-cut, definite answer. What you get are data-points that are more consistent with one answer than with another. So not every vegetative state patient responds to these kinds of instructions, those who do may do so to different levels of success… But I chose this paper because it has now been the topic of a lot of discussion, and it really gets to the conceptual issue of how do we know if someone is conscious, or whether we can ever really know? The back and forth is fascinating.

Your next choice, this video clip and the research based on it is just absolutely brilliant.

[Spoiler alert: follow the instructions in this 82-second clip before you continue reading!]

This phenomenon is known as inattentional blindness: Among people counting passes in the white t-shirt team, about 90 per cent – including me, when I first saw this – completely miss the gorilla. The phenomenon is a whole field of research in psychology nowadays. Why do people miss very obvious, highly-salient events? Under what conditions does this happen more than in other conditions? For example, if people are counting the black shirt passers, the chances of spotting the gorilla are increased, because there is more similarity between the gorilla and the people in the black shirts. Inattentional blindness was known before this research. There had been several demonstrations of it going back for quite a few years. But many of them did it with very quick flashes of pictures that you had to do some task with, and in one of them there would be an extra element and you were asked if you saw it. And that works, but it’s a lot less interesting than a big gorilla walking across the screen for nine seconds, stopping in the middle to beat his chest, and people actually having to walk around it to pass the ball to each other. What was so interesting to me was how a really, really simple instruction can block out half of your visual world.

How does it relate to consciousness?

Well, my first choice – the book Introducing Consciousness – dealt with the philosophical issue of how activity in a physical system can lead to something feeling like something. My second choice, the discussion of awareness in the vegetative state, looks at the issue of what it is about brain activity that defines our state of consciousness – whether we are conscious, not conscious, or something in between. This third choice, a demonstration of inattentional blindness, is about the content of our consciousness. We know that the brain can process a lot of things that it’s unaware of, for example words presented subliminally, too quickly to consciously see – we know there is something in our brain’s semantic system that can still process their meaning. There’s experimental evidence of that. The question is, in that case, what makes the distinction between the things that we see and become aware of, and the things that our eyes are exposed to but we remain unaware of? We walk around thinking our eyes are a bit like cameras, picking up the world around us and relaying whatever they see to the brain, and that what is relayed is what we’re aware of. But that’s simply not true. We remain unaware of a lot of what we see. And this is a pretty surprising or striking demonstration that gets that point across.

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