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How to measure consciousness
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Mind how you go Mark Pagel tours human consciousness with three influential ghosts for guides consciousness a place from which few ever return? In spite of having acquired a vastly improved understanding of the physical, chemical and neuronal structures of the brain, we seem little advanced over the ancient Greeks in our subjective understanding of this mysterious feature of our existence.
GIULIO TONONI’S charming book Phi is an account of consciousness that nods in its style to the writings of a fellow Italian. Yet while Dante had the poet Virgil to guide him on his journey through the circles of hell in the Divine Comedy, Tononi’s elderly traveller Galileo draws on the expertise of three great scientific minds. Journeying into the nature of consciousness he is led by a Francis-Crick-like character, someone who must be Alan Turing and finally Charles Darwin. Is Tononi trying to tell us that the vast philosophical morass of consciousness – what it is, where it resides, how it arises from a purely physical brain – is a kind of hell? And, like hell, is the scientific and philosophical study of
Frozen over On the Edge: Mapping North America’s coasts by Roger M. McCoy, Oxford University Press, £18.99/$29.95 Reviewed by Erin Wayman
BETWEEN 1492 and 1542, European explorers mapped the coastlines of South America, Central America, and much of the east and west coasts of North America. Yet it took a further 350 years of navigating treacherous Arctic
Can consciousness be understood as a measure of integrated information?
Trent Parke/Magnum Photos
Phi: A voyage from the brain to the soul by Giulio Tononi, Pantheon, £19.99/$30
It is still the case, for example, that each of us knows we have consciousness but can’t be sure anyone or anything else does. Mindful of this, Tononi, a neuroscientist at the University of Wisconsin-Madison, avoids the usual traps and lays out a computational theory that describes consciousness as arising from “integrated information”, a quantity he denotes with the Greek character Φ of his title. Think of it this way: your digital camera has a prodigious memory capacity but its millions of pixels
never “see” a photo. Your mind can because your brain actively constructs scenarios, tableaux and even simple perceptions from the integrated inputs of myriad specialised circuits. So Φ is a measure of that integration. Tononi’s approach can explain some curious phenomenology of consciousness. Why do we lose consciousness when we go to sleep? He would say that this is a time when information from the brain’s specialised circuits is no longer integrated. Why are brain seizures associated with a loss of consciousness? Again, seizures seem to block complex informational exchange. These ideas move us closer to grasping what consciousness is because, if Tononi is right, he can in principle measure varying degrees of consciousness among different people, or even different organisms. But what about bats – those famous subjects of debates on consciousness? Are we any closer to knowing what it is like to be one? Not yet, it seems, but perhaps now Tononi at least has students of consciousness travelling along the path to Paradise. n Mark Pagel is an evolutionary biologist at the University of Reading, UK. His latest book is Wired for Culture (Allen Lane/W. W. Norton)
waterways to finish the outline of By the 19th century, the the New World. Even then, the British –the main mappers of the North-West Passage remained Arctic – still hadn’t found a sea elusive. The triumphs and failures route connecting the Atlantic and of the centuries-long struggle to Pacific. But pride prevented them survey those Arctic shores are from giving up. Fortunately, the main focus of geographer expeditions started to collect data Roger McCoy’s On the Edge. about polar geology, climate and Back then, the far north was natural history. Those records even more frigid than today. The are now an important benchmark Little Ice Age, which began in the for researchers investigating 1300s and lasted for 400 years, climate change, McCoy explains. made the climate harsh and Yet some of the significance unpredictable: extensive sea ice “The expeditions follow the meant the region was navigable same script: a captain sets for only a few months of the year, sail, his ship gets stuck in and channels open one summer ice, sailors sit around...” might be frozen shut the next.
of these journeys is lost in what often feels like an endless list of expeditions that follow the same script: a captain sets sail confident, his ship gets stuck in ice, sailors sit around a lot, problems arise, men starve and the expedition is saved (or not). The repetition highlights the real failure of the Arctic explorers – their inability, or refusal, to learn survival tactics from the local people. And sadly it also highlights McCoy’s missed opportunity to breathe more life into an important era of our geographical history. n 4 August 2012 | NewScientist | 45
Mind how you go Mark Pagel tours human consciousness with three influential ghosts for guides consciousness a place from which few ever return? In spite of having acquired a vastly improved understanding of the physical, chemical and neuronal structures of the brain, we seem little advanced over the ancient Greeks in our subjective understanding of this mysterious feature of our existence.
GIULIO TONONI’S charming book Phi is an account of consciousness that nods in its style to the writings of a fellow Italian. Yet while Dante had the poet Virgil to guide him on his journey through the circles of hell in the Divine Comedy, Tononi’s elderly traveller Galileo draws on the expertise of three great scientific minds. Journeying into the nature of consciousness he is led by a Francis-Crick-like character, someone who must be Alan Turing and finally Charles Darwin. Is Tononi trying to tell us that the vast philosophical morass of consciousness – what it is, where it resides, how it arises from a purely physical brain – is a kind of hell? And, like hell, is the scientific and philosophical study of
Frozen over On the Edge: Mapping North America’s coasts by Roger M. McCoy, Oxford University Press, £18.99/$29.95 Reviewed by Erin Wayman
BETWEEN 1492 and 1542, European explorers mapped the coastlines of South America, Central America, and much of the east and west coasts of North America. Yet it took a further 350 years of navigating treacherous Arctic
Can consciousness be understood as a measure of integrated information?
Trent Parke/Magnum Photos
Phi: A voyage from the brain to the soul by Giulio Tononi, Pantheon, £19.99/$30
It is still the case, for example, that each of us knows we have consciousness but can’t be sure anyone or anything else does. Mindful of this, Tononi, a neuroscientist at the University of Wisconsin-Madison, avoids the usual traps and lays out a computational theory that describes consciousness as arising from “integrated information”, a quantity he denotes with the Greek character Φ of his title. Think of it this way: your digital camera has a prodigious memory capacity but its millions of pixels
never “see” a photo. Your mind can because your brain actively constructs scenarios, tableaux and even simple perceptions from the integrated inputs of myriad specialised circuits. So Φ is a measure of that integration. Tononi’s approach can explain some curious phenomenology of consciousness. Why do we lose consciousness when we go to sleep? He would say that this is a time when information from the brain’s specialised circuits is no longer integrated. Why are brain seizures associated with a loss of consciousness? Again, seizures seem to block complex informational exchange. These ideas move us closer to grasping what consciousness is because, if Tononi is right, he can in principle measure varying degrees of consciousness among different people, or even different organisms. But what about bats – those famous subjects of debates on consciousness? Are we any closer to knowing what it is like to be one? Not yet, it seems, but perhaps now Tononi at least has students of consciousness travelling along the path to Paradise. n Mark Pagel is an evolutionary biologist at the University of Reading, UK. His latest book is Wired for Culture (Allen Lane/W. W. Norton)
waterways to finish the outline of By the 19th century, the the New World. Even then, the British –the main mappers of the North-West Passage remained Arctic – still hadn’t found a sea elusive. The triumphs and failures route connecting the Atlantic and of the centuries-long struggle to Pacific. But pride prevented them survey those Arctic shores are from giving up. Fortunately, the main focus of geographer expeditions started to collect data Roger McCoy’s On the Edge. about polar geology, climate and Back then, the far north was natural history. Those records even more frigid than today. The are now an important benchmark Little Ice Age, which began in the for researchers investigating 1300s and lasted for 400 years, climate change, McCoy explains. made the climate harsh and Yet some of the significance unpredictable: extensive sea ice “The expeditions follow the meant the region was navigable same script: a captain sets for only a few months of the year, sail, his ship gets stuck in and channels open one summer ice, sailors sit around...” might be frozen shut the next.
of these journeys is lost in what often feels like an endless list of expeditions that follow the same script: a captain sets sail confident, his ship gets stuck in ice, sailors sit around a lot, problems arise, men starve and the expedition is saved (or not). The repetition highlights the real failure of the Arctic explorers – their inability, or refusal, to learn survival tactics from the local people. And sadly it also highlights McCoy’s missed opportunity to breathe more life into an important era of our geographical history. n 4 August 2012 | NewScientist | 45