Book Review |
Not all in the Brain
At first glance, Chris Frith's brilliant short book is just the thing for a favourite niece wondering about a career in medicine or neuroscience. It is written with wit and charm and a good deal of rueful humour: ‘Psychologists and neuroscientists have studied working memory intensively, but have yet to reach agreement about precisely what it is they are studying’ (p. 4) is a characteristically acerbic observation. Little prior knowledge is required of the reader; for example there are line diagrams of synapses, explaining basics such as ‘how one nerve cell communicates with another’. My initial impressions were deceptive. I would still recommend it to the beginner—not least for its wonderful bibliography—but it has even more to offer the cognoscenti, in particular those who have not yet given up thinking about the larger problems of the relationship between the brain, the mind, consciousness, knowledge and human freedom.Frith's central hypothesis—that the mind is itself a brainchild—is a bold, clear, indeed radical, reworking of a way of thinking increasingly in the ascendant over the last half century, according to which the world we inhabit is a mental model which often has only a tangential relationship to what is ‘really out there’. Frith's version of the ‘mental models’ approach is particularly provocative, and thought-provoking, because he is unequivocal in his claim that it is the brain that ‘makes up the mind’; and in turn, the brain models, or houses the model of the world.
This complex hypothesis is ultimately rooted in Frith's materialist ontology and his belief that ‘[e]everything that happens in [the] mind (mental activity) is caused by, or at least depends upon, brain activity’ (p. 23). From this, he concludes not only that the brain makes up the mind but also that ‘The contents of the mind are not real’ (p. 16). The brain is, therefore, primarily a source of illusions: ‘By seeing through these illusions created by our brain, we can begin to develop a science that explains how the brain creates the mind’ (p. 17). Much of his book, therefore, is devoted to an examination of the brain's illusions and how they are created. Frith observes the damaged brain, the normal brain and ‘what the brain tells us about the body’.
The damaged brain ‘knows but doesn't tell’: people with amnesia may acquire skills without any memory of the process of acquiring them; and individuals with ‘blindsight’ respond to visual cues in the absence of visual experience. The brain may ‘tell lies’ as in visual or auditory hallucinations associated with severe visual or hearing loss—the Charles Bonnet Syndrome. It may ‘create false knowledge’ in people with epilepsy. You can make your brain lie to you by taking drugs such as LSD.
Those with undamaged brains have no grounds for smugness: ‘even if your brain is intact and functioning perfectly normally, what it tells you about the world may still be false’ (p. 39). The most pervasive illusion is that we perceive directly what is out there. In fact the object of perception is the conclusion of what Helmholz characterized in the 19th century as ‘an unconscious inference’ beyond what arrives at our sense endings. We imagine we see a three-dimensional visual scene in vivid detail when in fact such a scene is constructed from a two-dimensional image on the retina whose edges are blurred and colourless. We are blind to our blind spot. The transformation of sense experience into perceptions will draw on prior beliefs: we have an overwhelming propensity to perceive what we expect to perceive. Our spectacular ability to overlook certain major changes in visual scenes underlines how we tend to perceive not what is in front of us but the gist of it.
Perception of a stimulus is greatly influenced by preceding stimuli even when we are not aware of the latter (‘subliminal perception’): neuro-imaging shows activity in response to the prior stimulus, irrespective of whether the subject is aware of it. Our brain, it appears, ‘doesn't tell us everything it knows’ (p. 47). The extent to which the brain seems to be calling the shots is underlined by the stubbornness of visual illusions. No amount of knowledge or additional experience can stop me seeing straight lines as bent in the Hering illusion, or prevent a synaesthete prone to coloured hearing from experiencing the hue of cries. And then there are dreams, and the hallucinations of the insane. And so on.
Even the sense that we have direct access to our own bodies is yet another illusion created by the brain. Frith argues this on the grounds that the portion of the world colonized by first-person consciousness is somewhat variable. It is possible to mistake a part of the outside world for your body, as in the party trick where you are duped into referring experiences in your own upper limb to a rubber arm. Prostheses, and even tools, become incorporated in our body schemata. We may be unaware of what our limbs are doing when we are put into situations that distort our appreciation of their actions. Phantom limbs, anosagnosia, the alien hand syndrome, actions prompted by prior hypnotic suggestion, and Benjamin Libet's experiments in which the initial brain activity associated with movement occurs before the subjective experience of intending the action, all indicate that the boundary between our body and the world, and between that part of the world over which we have control and that over which we do not, is porous and our reading of the scope of our own agency unreliable.
Our brains create the illusion that we have direct contact with the world, including our own bodies, ‘by hiding from us all the complex processes that are involved in discovering about the world’ (p. 81). Such processes have to be hidden. If we were aware of all that was going on, ordinary actions would be accompanied by neural pandemonium. We suppress, for example, activity that is not necessary for us to predict what is going to happen next; which is why, as demonstrated in Frith's own famous experiment, self-tickling (when we know what is going to happen next) is associated with lesser brain activity than being tickled by another (when we don't); why, in short, is self-tickling not ticklish.
Given that our brain ‘actively creates pictures of the world’ (p. 85) how does it get it right? Associative learning—the conditioning of reflexes and the like—enables us to discover which of our actions influence the future, and indeed, to predict reward—a function mediated by dopaminergic pathways; and we learn as much by erroneous as by correct prediction. Associative learning enables the brain to construct a map of the world. This is essentially ‘a map of value’, which intimately ties our bodies to the world around us so that we can respond in the quick and efficient way essential for survival.
Frith is aware that if the brain didn't get things right—or right enough for survival—there would be no brain. A life of unchallenged fantasy is a luxury that nature does not permit and certainly would not foster through evolution. However, he has already argued that the contents of the mind are not real. He has to explain, therefore, how (in the words of a chapter heading) ‘Our Perception of the World Is a Fantasy That Coincides with Reality’. The brain, Frith says, is an ideal Bayesian observer—using evidence in the most economical way to engage in an iterative process in which it progressively corrects its predictions in the light of sensory information. Once the error is sufficiently small, the brain ‘ "knows" what is out there’ (p. 125). Some of these predictions will be ‘hard-wired’ by evolution—this accounts for the stubbornness of many illusions—but they are adjusted to particular situations by sensations that ‘correct’ them and by actions that are based on perceptions that may or may not turn out as expected. The models constructed by the brain are refined to give the best possible predictions of my sensations as I act upon the world. We are not, however, slaves of our senses: ‘Through its controlled use of fantasy, our brain escapes from the tyranny of our environment’ (p. 136). On the other hand, the unexpectedness of reality, its coefficient of resistance as it were, distinguishes it from freewheeling fantasy and prevents fantasy from taking over.
So far, Frith has focused on the isolated brain-mind. Neither we nor our models of the world are windowless monads. We are aware that there are others in the world, conscious as we are, who also construct models, from viewpoints that are different from ours. By observing the movements of others, we may infer their goals and intentions. We are, it would seem, exquisitely adapted to tune into others in this way. From infancy we pay particular attention to faces and have an extraordinary capacity to detect eye movements and infer from them what others are interested in: gaze is a bi-directional pointer that picks out both an object of interest and the other's interest in it. We have a tendency to look where we see others looking, and more generally, courtesy of the complex system of mirror neurones, to imitate what we see they are doing.
Our ability to translate the visual appearance of another's movement into the motor programmes necessary for imitation is extraordinary, as is the fact that the pressure to imitate is greater when the observed movement is generated by a human being rather than a robot. Empathy is based on the partial overlap of the brain activity seen when, for example, I observe another in pain, and that which is aroused when I experience pain myself. Most interestingly, the processes by which we determine that an event is an action we have carried out, rather than merely something happening in our body, is the same as when we are trying to detect agency in another. We do not, it seems, have privileged access to the truth about whether we are or are not agents. We can be deceived into believing we are doing things that merely happen; conversely, people with schizophrenia may imagine that even their own thoughts are being thought by others and inserted from without. The mechanisms by which we infer these fundamental facts about ourselves are precisely those that enable us to read the minds of others. To paraphrase Rimbaud, ‘ "Je" aussi est un autre’.
The brain that models the minds of others is well prepared to live in the community of minds that is culture. Indeed, ‘the brain creates culture’ out of communications in which we are aware of how what we say is interpreted. We observe how others respond and, if this does not correspond to what we expected or intended, we adjust how we communicate. Our face-to-face communications are continually modified by the models we build of others’ mental models of the world. One of the supreme manifestations of culture is science, in which we make models of the world as a whole. In neuroscience we model how our brains make models of the world. And with this, Frith's account of the mind made by the brain approaches completion: neuroscientists are brains modelling their own modelling activity. Consistent with this view, Frith rejects the distinction between himself and his brain: the ‘I’ that wrote Making up the Mind is also created by Frith's brain and, as such, is an illusion.
The very clarity and boldness with which Frith expresses his ideas about the relationship between the brain, the mind and the world we share makes them particularly vulnerable. There are obvious places to begin a critique. The first is the reliance he places on the argument from illusion: that because we get things wrong a lot of the time, we must be in contact, not with how things are, but rather with our model of how things are; and this may not correspond to reality. The trouble with the globalization of illusion—which at times he seems to subscribe to—is that eventually it squeezes out the notion of an illusion because there is no reality with which to make the contrast. As Gilbert Ryle pointed out ‘there can be false coins only where there are coins made of the proper materials by the proper authorities'. And in practice, while optical illusions remind us that what we see is not always what is there, their comparative rarity underlines that what we see most usually is there. Pink elephants and headless horses are outnumbered by real cups and real saucers; otherwise the former would not attract such interest.
However, just when you think Frith has fallen entirely victim to the fallacy of the argument from illusion he rescues his brain from solipsism with his claim about the brain being ‘an ideal Bayesian observer’ so that its illusions can be corrected in accordance with sensations in order that they approximate to reality. But if the mind itself is an illusion, it is difficult to see how it can be sufficiently disillusioned to wake up to what is ‘really’ there. Sensations do not seem to me to be epistemologically more privileged than perceptions, even the sensations associated with actions that may go right (if we have got things right) or wrong (if we have got things wrong). If we get the piece of the world that is ourselves—our body—so routinely and fundamentally wrong (including the question of which bits of the world are ourselves), and if, also, we are our brains and our brains are bits of the world on an ontologically equal footing with the rest of the world, it is difficult to see how we can approach the truth about what is there by progressive correction of our prior erroneous ideas. The fact that a piece of matter should have ideas at all—about itself, about other brains and about the world at large—is also difficult to accommodate in the Frith's ‘neuralized’ reality.
Even more worrying is the extent to which Frith relies on the brain to do things that we might normally ascribe to fully developed human beings. This kind of thinking by transferred epithet goes all through Frith's brain-talk—and indeed through much of cognitive neuroscience—like ‘Brighton Rock’ through Brighton rock. We have fairly naked anthropomorphism even at the unicellular level: ‘Nerve cells are essentially signalling devices’ (p. 82). ‘Activity in dopamine nerve cells’ he claims ‘signals an error in our prediction’ (p. 95); and ‘we can see this predictive activity if we look directly at the activity in the nerve cells’ (p. 82). Of course, once we accept that its individual cells are so smart, we are softened up to accept that the brain as a whole is ‘an ideal observer’ that ‘notices’, ‘predicts’, ‘produces appropriate models’, ‘tricks you into thinking something’, ‘tells us about the world’, ‘knows so much about the world without this knowledge ever reaching our awareness’, ‘actively creates pictures of the world’, ‘creates pushes and pulls’, ‘creates the illusion that I am an independent being’, ‘works hard’, ‘discovers what is out there’, ‘creates the feeling of agency’ and ‘creates the sense of self’. The brain, it seems, is smarter than we are. And rather paternalistic, too. As we have seen, it refrains from bothering our little heads with many of the things it knows: most of what it knows never reaches our consciousness. One could be forgiven for thinking that brains are just like people only much cleverer—brainier, perhaps.
By ascribing the highest level activities—such as creating illusions of agency, selfhood and so on—to the brain, Frith gets a free-pass across the mind-brain barrier. And sometimes he doesn't even need this free-pass, since the barrier is often crossed before the nervous system is arrived at. ‘Our eyes and ears’ he tells us ‘pick up information about the physical world and transmit it to our minds’. Information, apparently, is just lying there for the taking in the material world, in rocks and trees and ice cream cornets and sugar lumps; the mind simply receives it. Under the spell of such talk, the differences between synapses and citizens are elided, except insofar as citizens are, seemingly, less real than synapses; and particularly as citizen's subjective experiences, even basic ones such as qualia, don't really have a place in the material world. Not only is it unclear how activity in neurones stimulated by light of a certain wavelength could ‘represent’ red, but also it is difficult to understand why they should bother to register the whole business. Or, more generally, why the brain should bother to invent a mind—prone as it is to illusions that have to be corrected—instead of being plugged ever more snugly into the material world, of which it is a part, by entirely mindless mechanisms.
It is also rather surprising that brains such as those attached to neuroscientists could ever come to know just how clever the brain is and, indeed, how reality differs from the way our brains present it to us—how ‘red’ light energy, for example, is not red in itself. How can neuroscientists outwit their vastly superior brains to unmask what they are up to? We have already seen how Frith teeters on the verge of philosophical scepticism as to whether or not we gain access to an extra-mental (or extra-cerebral) reality, which we more or less see aright. He certainly makes it difficult for himself to understand how he, or his brain, could have arrived at the notion—central to his book—that we model reality; or that ‘our perception of the world is a fantasy that coincides with reality’—an assertion that presupposes an ability to stand outside of both the perception and the reality and compare the two. Where is that standpoint located: in another bit of the brain? This is even more difficult to understand, given that the ‘I’ is created by the brain: ‘I am firmly convinced that I am the product of my brain, as is the awareness that accompanies me’ (p. 23). The illusion of the ‘I’ is the product of the brain washing itself. The self-washed brain produces an illusion called Chris Frith.
One wonders, of course, what function ‘I’ serves; why the brain creates this illusion; and what difference, if it is an illusion, this makes to how Frith thinks of himself and of other people. And, if first-person being really boils down to third-person neural activity, what is the origin of viewpoints in a viewpointless material world? What makes the brain ‘my brain’ and that which it models ‘my’ take on the world? How does Frith account for all those indexicals—particularly personal pronouns such as ‘I’, ‘me’, ‘my’, ‘our’ and so on—that pepper his account of the brain? When, for example, he says that ‘We are simply not aware of all the inferences and choices our brain has constantly to make’ (p. 81) shouldn't we worry about the status of ‘we’ and ‘our’?
The problems are particularly knotty since Frith, a materialist, argues that ‘the distinction between the mental and the physical is false. It is an illusion created by the brain ...’ (p. 17)—though he undermines this by saying that the mental is illusory while the physical is real—quite a serious distinction, one would have thought. And a few pages earlier, noting that ‘Brain activity can indicate that mental activity is occurring and, to that extent, provides an objective marker of subjective experience’, he adds that ‘brain activity is not the same as mental experience’ (p. 15). We have already quoted his claim that mental activity ‘is caused by, or at least depends upon, brain activity’, though it is difficult to see how colourless causes such as incident electromagnetic radiation could cause the experience of red—even less (to use the favourite term) be ‘represented’ by the latter. We seem to be in the grip of quite a dense muddle.
The reduction of mind to, mainly unconscious, brain mechanisms becomes much easier if one focuses on the things that happen in the brain of which we are unaware and at the same time that the brain is aware of them on our behalf. Frith emphasizes again and again that the ‘brain knows and does without me being aware of it’ (p. 189). One would like to know whether the brain knows that it knows what it knows or whether it, too, is unaware of knowledge. If it is, then the knowledge seems to lack a (conscious) knower. This is serious because, at the very least, knowledge, even if it is not currently consciously known, should in principle be accessible to consciousness—and not just to the consciousness of third party such as a neuroscientist. If I claimed to be very knowledgeable but added that I was not conscious of anything I knew, you might treat my claim with a certain amount of disdain. While knowledge does not require continuous awareness of the known, knowledge cannot be entirely separated from consciousness.
More importantly when, as it so often does, knowledge takes the form of facts, or, more broadly, propositional awareness, it belongs, as Donald Davidson repeatedly emphasized, not to a solitary organism (as perhaps sensations might) but ‘to a community of minds’. One can credit a stand-alone brain with knowledge only by removing from knowledge, its two characteristic features: consciousness and its location in the community of consciousnesses that is the culture in which we pass our lives.
The transcendence of the organism that characterizes knowledge is difficult to account for in Frith's neurophilosophy. Which is not surprising: by reinserting the mind back into the stand-alone brain—and indeed mind-like bits into minute bits of the brain such as neurones—he takes back our ability to transcend our organic basis. This transcendence cannot be achieved merely by neural activity seen as the cerebral effects of extra-cerebral material causes. It begins with conscious awareness of that which we are not: with intentional relations to objects that are explicitly experienced as other than ourselves, who are the experiencing subjects. This is the ground floor of a cognitive evolution that leads to factual knowledge: ‘that’ such and such is the case. In such knowledge, the knower is conscious—of the known and of herself and of the difference, and the relationship, between the two. This is a far cry from unconscious ‘mind’ that is made up of the mechanisms in a knowing but unaware brain, seen in isolation.
I anyway have a serious problem with accounts of the mind that regard it as only unimportantly conscious. Frith is happy to assert that his book about the mind ‘is not about consciousnesses. For me the essence of minds is that they suffer and enjoy, they try to make things happen, and they are happy when they succeed and less so when they fail. Of course, there are mechanisms underlying conscious activities—such as willed action or deliberate thought—that are not themselves conscious. These mechanisms extend well beyond the brain. When I head purposefully off to the pub to meet someone in order to persuade them to collaborate with me on a research project, I am quite unaware of the breaking and re-forming of the cross-bridges that enable my muscles to contract so that I can propel myself to my destination. This does not make my action unwilled or essentially unconscious. The difference between the underpinning mechanisms and the conscious action guided by a sustained explicit purpose cannot be captured in physiological terms. Just as neurophysiology cannot capture what is fundamentally different between having an epileptic fit and deciding, after much agonizing indecision, to conceal that fact from one's employer. Invoking activity in more of, or different places in, the brain, does not deliver this difference. When Frith observes that ‘brain imaging studies suggest that physical pain and the pain of social rejection involve the use of the same brain regions’ (p. 6), he sees this as confirmation that psychology has now come of age as a science because it can now study all sorts of higher order experiences. I see it as incontrovertible evidence of the limitations of brain imaging and how little it can tell us about human consciousness.
The journey from excitable tissue to membership of the community of minds in which we live our lives and have our (importantly) conscious being has been a long one. We shall not, therefore, find the community of minds, and our everyday lives, in the behaviour of excitable tissue, even though the latter is a necessary condition of the former. The illusion that we can do so arises from neuroscientists’ anthropomorphizing bits of the brain. When they find that those bits don't deserve the human epithets conferred upon them, they tend to question whether human attributes such as free will, access to reality, self-knowledge or progress towards objective truth, which are evident in the community of minds, really exist. If you fail to find something when you look in the wrong place or in the wrong way, it is tempting to conclude that it doesn't exist. Physicists can't find free will, the self, or the ‘I’ in atoms, but they don't (typically) conclude that, since we are made of atoms, these things don't exist. Anyway, denying their reality puts science itself, and its large truth claims in a rather awkward position. Often, as I read Making up the Mind, I could hear the sound of the author sawing the branch upon which he was sitting.
I read this short book in a couple of hours. I shall be arguing with it (and myself) for years. While I am more impressed by Frith the scientist than Frith the (unwilling or unwitting) metaphysician, the questions he raises so clearly bring into focus the need for a new approach to the interface between neuroscience and the philosophy of mind; for a ‘critical neuro-epistemology’, which does not rely on relentless anthropomorphizing of neural activity to make sense of the relationship between our brains and our conscious selves. Frith's luminously intelligent book also raises interesting questions about how it is possible to make serious scientific progress, on the borders of metaphysics, while still thinking inside a framework that is an ontological and epistemological muddle. This second-order question raises first-order questions about the relationship between language, human consciousness and what is ‘out there’.
At any rate Chris Frith—the person, the mind, the scientist, the author, the extraordinarily talented representative of the community of minds—cuts an even more impressive figure than Chris Frith's brain.
Emeritus Professor of Geriatric Medicine
University of Manchester
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