Showing posts with label Nick Bostrom. Show all posts
Showing posts with label Nick Bostrom. Show all posts

12 Jul 2011

Conference Version of Do Posthumanists Dream of Pixilated Sheep? Bostrom & Sandberg's Brain Emulation, Examined and Critiqued

by Corry Shores
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The following is from a conference presentation at the University of Twente, for the Society for Philosophy & Technology, June 2009.


Corry Shores

Do Posthumanists Dream of Pixilated Sheep?
Bostrom and Sandberg's Brain Emulation,
Examined and Critiqued

Enhancement technologies may someday give us capacities far beyond what we dream humanly possible. We could become post-human. Nick Bostrom & Anders Sandberg suggest that we might survive our body's death by living as a computer simulation. They issued a report from a conference where experts in all relevant fields collaborated to determine the path to "whole brain emulation." This technology will in the very least be an effective research tool for the neurosciences. It could even aid philosophical research too. Their "roadmap" defends certain philosophical assumptions required for this technology's success. So by determining the reasons why it succeeds or fails, we can obtain empirical data for philosophical debates regarding our mind and selfhood. I have chosen four issues to discuss: emergentism, analog vs. digital, unpredictability, and personal identity.

Brain emulation succeeds if a computer program replicates human neural functioning. Yet for the authors, its success increases when it perfectly replicates one specific person’s brain. She might then survive her body’s death by living as the simulation.

This prospect has posthumanist proponents. Their view presupposes certain traits of human consciousness and selfhood. Hans Moravec for example thinks our personal identities exist independently to our bodies.

According to his pattern-identity theory of selfhood, we are no more than the patterns and the processes found in our brains and bodies. William Bainbridge explains that we are neither man nor machine. We are just the dynamic patterns of information that can be realized in a wide variety of materials. Hence our personal patterns might be found in this body or in that computer. Either way we are the same person.

To emulate someone’s neural patterns, we first scan a particular brain to obtain precise detail of its structures and their interactions. Using this data, we program a simulation that will behave essentially the same as the original brain. Now first consider a gnat’s wild flight pattern. It seems irrational and random. But the motion of a whole swarm is smooth, controlled, and intelligent, as though the whole group of gnats has a mind of its own. To simulate the swarm, perhaps we will not need to understand how the whole swarm thinks. We instead just learn the way one gnat behaves and interacts with other ones. When we combine thousands of these simulated gnats, the swarm’s collective intelligence should thereby appear. Whole brain emulation presupposes this principle. The simulation will mimic the human brain’s functioning on the cellular level. Then automatically, higher-and-higher orders of organization should spontaneously arise. Finally human consciousness might emerge at the highest level of organization.

Early in this technology's development, we should only expect simpler brain states, like wakefulness and sleep. But in its ultimate form, whole brain emulation would enable us to make back-up copies of our minds. Then we might somehow survive our body’s death.
According to Bostrom & Sandberg, whole brain emulation should replicate all the original brain’s relevant properties so to produce a 1-to-1 model of the brain’s functioning. In this sense, the brain and its emulation are black boxes. We feed each one on its own the same sequence of stimuli. If they both respond with the same sequence of reactions, then they are functionally equivalent. In this way, the same mind could be realized in two physically different systems. Hilary Putnam claims that electronic computers can be functionally equivalent to mechanical ones and even to humans using pencil and paper. Their insides may differ drastically, but their outputs are identical.

There are various levels of emulation success. The highest ones are the most philosophically interesting.

When the technology achieves individual brain emulation, it produces emergent activity characteristic of one particular brain. With further success, we would emulate someone’s personal identity. Perhaps somehow it would be numerically the same person. But at least it would continue-on as that person even after her body dies. We achieve such a simulation when it becomes rationally self-concerned for the brain it emulates.

Minds emerge from the brain’s pattern of physical dynamics. If you replicate this pattern-dynamic in some other physical medium, the same mental phenomena should likewise emerge. One mind would then be realized in a multiplicity of different physical embodiments. So whole brain emulation’s success would provide evidence for the theory of multiple realizability.

According to emergentist theories, all reality is made-up of a single kind of stuff. But its parts aggregate and assemble into dynamic organizational patterns. The higher levels exhibit properties not found in the lower ones. But, there cannot be a higher order without lower ones underlying it.

Consider the H2O molecule. It does not itself bear the properties of liquidity, wetness, and transparency. However, a large enough aggregate of water molecules will exhibit these properties.

In our brains, no one single neuron is conscious. Yet, our minds emerge from the complex dynamic pattern of all our neurons’ parallel computations. Roger Sperry offers compelling evidence. There are "split brain" patients whose right and left brain hemispheres are disconnected from one another. Nonetheless, they maintain unified consciousness.

William Hasker offers the analogy of magnetic fields, which are distinct from the magnets producing them. The iron atoms themselves need to be organized in alignment in order for a magnetic field to emerge on a higher scale. In a similar way, the particular organization of the brain’s neurons generates a field of ‘consciousness.’ This emergent consciousness-field permeates and haloes our brain-matter, occupying its space and traveling along with it.

Not everyone agrees that the mind emerges from the brain. Todd Fineberg is one example. Now in fact, he does think that consciousness results from the complex interaction of many layers of neural organization. However, he argues that consciousness does not get squirted-out from neural activity and thereby obtain a life of its own. Instead, the layers of neural activity are all mutually interdependent and simultaneously cooperative.

Consider for example when we recognize our grandmother. One layer of neurons transmits information about the whole visual field. Another layer picks-out lines. Another one, shapes. Finally the information arrives at the grandmother cell, which only fires when it is she that we see. But this does not make the grandmother cell emergently higher. Rather, all the neural layers of organization must work together simultaneously to achieve this recognition. The brain is a vast network of interconnected circuits. So we cannot say that any layer of organization emerges over and above the others.

Fineberg’s objection may prove problematic for whole brain emulation. Bostrom & Sandberg explicitly state that we only need to simulate the lower levels of activity.

But if Fineberg’s holistic theory is correct, we cannot only emulate the lower levels and expect the rest to spontaneously emerge. For, we need already to understand the higher-levels in order to program the lower ones. So, whole brain emulation’s emergentist assumptions might not express the actual way that consciousness appears.

Notice how in the recent past, many digital technologies have replaced analog ones. It would seem that these two sorts of quantity-representation reside in contrary worlds: the continuous versus the discrete. An abacus is digital. It computes one discrete value or another, but it is blind to the values between its units. When we count to two on our fingers, meaningless empty space spans between our digits. So spreading our fingers further apart does not change their numerical value.

Slide-rules, however, are analog. One ruler slides against another continuously. So it may calculate any possible real number along the continuum. It could potentially compute and display irrational numbers like pi or the golden ratio. However, a digital computer would never cease calculating into lower digit places. For, there can be no final figure when rendering irrational numbers into digits. But, if you move the slide rule from three to four, you will for one instant display pi. Analog is dense. Between any two values is already a third one, and lying between those are yet even more, and so on infinitely. On account of this infinite divisibility, analog can compute and display an infinity of different values found within a finite range. But like the gaps between our fingers, digital at some point will be blind to a middle value, no matter how precise it is. So, because analog computers can deal with an infinity of values, they have more computing potential for certain applications.

Our emulated brain will receive simulated sense-signals. Does it matter if they are digital signals rather than analog? Many audiophiles swear by the unsurpassable superiority of analog. It might be less precise, but it always flows like natural sound waves. Digital, even as it becomes more accurate, still sounds to them artificial or cartoon-like. In other words, there might be a qualitative difference to how we experience analog and digital stimuli, even though it might take a person with extra sensitivities to bring this difference to our explicit awareness.
And if the continuous and discrete are so fundamentally different, then maybe a brain computing in analog would experience a qualitatively different feel of consciousness than if the brain were instead computing in digital.

Perhaps digital emulations might even produce a mental awareness quite foreign to what humans normally experience.

Bostrom’s & Sandberg’s brain emulation exclusively uses digital computation. But, they acknowledge the argument that analog and digital are qualitatively different. And, they admit that implementing analog in brain emulation could present profound difficulties. Yet, there is no need to worry, they say.

They pose what is called “the argument from noise.” Analog devices always take some physical form. It is unavoidable that interferences and irregularities, called noise, will make the analog device imprecise. So analog might be capable of taking-on an infinite range of variations. However, it will never be absolutely accurate, because noise always causes it to veer-off slightly from where it should be. Yet digital has its own inaccuracies. It is always missing variables between its discrete values. Nonetheless, digital is improving. Little-by-little it is coming to handle more variables. It is filling in the gaps. Digital will never be completely dense like analog. Values will always slip through its fingers. And analog will always miss its mark. But soon the distance between digital’s smallest values will equal the distance that analog veers-away from its proper course. Digital’s blindness would then match analog’s sloppiness. So, we only need to wait for digital technology to improve enough that it can compute the same values with equivalent precision. Both will be equally inaccurate, but for fundamentally different reasons.
Yet perhaps the argument from noise reduces the analog/digital distinction to a quantitative difference rather than a qualitative one. And analog is so prevalent in neural functioning that we should not so quickly brush it off.

Note first that our nervous system’s electrical signals are discrete pulses, like Morse code. In that sense they are digital. However, the frequency of the pulses can vary continuously. As well, there are many other neural quantities that are analog in this way.

Fred Dretske argues that our memories store information in analog. We might consider an event that occurred somewhere within a 15 minute time-span. But later, we also might search our memory for finer details to indicate more specifically when that event occurred. Because we can always further refine our remembered determinations, it could very well be that our brains record data in analog form.

But suppose anyway that the argument from noise is correct, and that we can dismiss analog’s computational superiority. Would there still be some reason to implement analog technology?
Recent research on neural-network learning supplies an answer. Analog noise interference is significantly more effective than digital at aiding adaptation. Being "wrong" allows neurons to explore new possibilities for computational values and connections. This enables us to learn and adapt to a chaotically changing environment. Using digitally-simulated neural noise might be inadequate. Analog is better. For, it affords our neurons an infinite array of alternate configurations. Hence, in response to Bostrom’s & Sandberg’s argument from noise, I propose this argument for noise.

Analog’s inaccuracies take the form of continuous variation. In my view, this is precisely what makes it necessary for whole brain emulation.

Neural noise can result from external interferences like magnetic fields. Or internal random fluctuations might make the signals unpredictable. In both cases, chance & chaos reign our brains. And in fact, these random, indeterminate, and probabilistic events assist our brain’s computations. It implements noise to keep us adjusted to the world’s changes and uncertainties.

Some also theorize that noise is essential to the human brain’s creativity. Johnson-Laird claims that creative mental processes are never predictable. On this basis, he suggests a way to make computers think creatively. We make them alter their own functioning by submitting their programs to artificially-generated random variations. According to Daniel Dennett, such indeterminism is precisely what endows us with what we call free will. Likewise, Bostrom & Sandberg suggest we introduce random noise into our simulation by using pseudo-random number generators. They are not truly random, because eventually the pattern will repeat. But if it takes a very long time before the repetitions appear, then probably it would be sufficiently close to real randomness. It would be a major obstacle, Bostrom & Sandberg admit, if artificial noise is not random enough for whole brain emulation.

Research suggests that we may characterize our neural irregularities as pink noise, or what is called 1/f noise. Benoit Mandelbrot classifies 1/f noise as what he terms “wild randomness.”

This sort of random might not be so easily simulated. The stock market for example is wildly random. In such natural systems, astronomically improbable fluctuations occur frequently. There is no way to predict when they will appear or how drastic they will be.

For this reason, he considers wild variation to be a state of indeterminism that is qualitatively different than the usual mild variations we encounter at the casino. For, there is infinite variance in the distributions of wild randomness. Anything can happen at any time. He says, “the fluctuation from one value to the next is limitless and frightening.” And this is the wildness of our brains.

Paul Shepard considers our minds to be wild in an even more literal sense: we are wild animals. He distinguishes tameness from domestication. Cows are domesticated. They have been bred to suit our needs. And now their genes would probably not prepare them to live in the wild without human protections. But the human species has merely been tamed by culture and not domesticated like cows. Genetically, we are still the same wild creatures who hunted the Pleistocene savannas. So to emulate the human brain is to simulate the workings not of a rational machine, but of a wild animal. He writes, “The savage mind is ours! ... as a species we have in us the call of the wild.”

But let’s suppose that the brain’s wild randomness can be adequately simulated. Will brain emulation still attain its fullest success of perfectly replicating a specific person’s own identity? Bostrom & Sandberg recognize that neural noise will prevent precise one-to-one emulation.

However, they think that the noise will not prevent the simulation from producing meaningful brain states. But to pursue further the personal identity question, let’s imagine that we want to emulate a certain casino slot machine.

A relevant property is its unpredictability. So, do we want the emulation and the original to both give consistently the same outcomes? That would happen if we precisely duplicate all the original’s relevant physical properties.

But what about its essential unpredictability? The physically-accurate emulation could predict in advance all the original’s forthcoming read-outs. Or instead, would a more faithful copy of the original produce its own distinct set of unpredictable outcomes? Then we would be replicating the original’s most important relevant property of being governed by chance.

The problem is that the brain’s 1/f noise is wildly random. So suppose we emulate some person’s brain perfectly. And suppose further that the original person and her emulation have an identity merger where each one somehow mistakes themselves for the other. Yet, if both minds are subject to wild variations, then their consciousness and identity might come to differ more than just slightly. They could veer-off wildly. Perhaps our very effort to emulate a specific human brain results in our producing an entirely different mind altogether.

Whether this technology succeeds or fails, it still can advance a number of philosophical debates. It could tell us if our minds emerge from our brains; if the philosophy of artificial intelligence should take analog more seriously. We might learn whether our brain’s randomness is responsible for creativity, adaptation, and free choice; or, if this randomness is the reason our personal identities cannot be duplicated. The only failure, as I see it, is if we neglect this technology’s philosophical potential.

14 Jun 2009

Conclusion; Bostrom and Sandberg's Brain Emulation, Examined and Critiqued. Section 6


by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

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[Posthumanism, Entry Directory]
[Other entries in this paper series.]

[The following is tentative material for my presentation at the Society for Philosophy & Technology Conference this summer.]





Corry Shores


Do Posthumanists Dream of Pixilated Sheep?

Bostrom and Sandberg's Brain Emulation,

Examined and Critiqued


Section 6:


Conclusion



I do not discourage this technology’s development. I hope in fact that my critical objections are wrong. For that way we will have reason to believe that Bostrom & Sandberg’s philosophical assumptions are in fact correct. This would lend support to the theories that our minds are emergent phenomena, that analog technologies are unnecessary for artificial intelligence, that we may artificially simulate our brain’s randomness that is essential for creativity, adaptation, and perhaps free choice, and that this randomness does not make it impossible to replicate someone’s personal identity. In this sense, the technology can never really be a failure. For even if results indicate it will never succeed, that lends support to the contrary philosophical assumptions.



Even While Men’s Minds are Wild?; Bostrom and Sandberg's Brain Emulation, Examined and Critiqued. Section 5


by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

[Central Entry Directory]
[Posthumanism, Entry Directory]
[Other entries in this paper series.]

[The following is tentative material for my presentation at the Society for Philosophy & Technology Conference this summer.]




Corry Shores


Do Posthumanists Dream of Pixilated Sheep?

Bostrom and Sandberg's Brain Emulation,

Examined and Critiqued


Section 5:


Even While Men’s Minds are Wild?



Neural noise can result from external interferences like magnetic fields. Or internal random fluctuations might make the signals unpredictable. (Ward 116-117) In both cases, chance & chaos reign our brains. According to Steven Rose, our brain is an “uncertain” system on account of “random, indeterminate, and probabilistic” events that are essential to its functioning (Rose 93). Alex Pouget and his research team recently found that the mind's ability to compute complex calculations has much to do with its noise. The word noise is misleading, he says, because it implies something goes wrong. But these unpredictable irregularities are the mind’s way of running at optimum performance. Our mind produces noisy signals to represent the uncertainty of the world around us. Pouget explains,

if we want to do something, such as jump over a stream, we need to extract data that is not inherently part of that information. We need to process all the variables we see, including how wide the stream appears, what the consequences of falling in might be, and how far we know we can jump.

In this way, the brain is flooded with countless variables. And the neurons transmit various signal patterns for the same stimulus. This allows us to estimate margins of error. We then use a probabilistic inference to make what is most likely to be the best decision. (Pouget, interview with Science Daily) So we might jump the stream, if probably we can cross it, even though we can never be certain about such matters.

Some also theorize that noise is essential to the human brain’s creativity. Johnson-Laird claims that creative mental processes are never predictable. (Johnson-Laird, The Computer and the Mind 256) He hypothesizes that we could make a machine creative by programming it to alter its own functioning according to generated random variations. (Human and Machine Thinking, 119-120) This would produce what Ben Goertzel refers to as “a complex combination of random chance with strict, deterministic rules.” (Goertzel 119) And according to Daniel Dennett, this indeterminism is precisely what endows us with what we call free will. (Dennett 295, cited in Dartnall 37) Likewise, Bostrom & Sandberg suggest we introduce random noise into our simulation by using pseudo-random number generators. They are not truly random, because eventually the pattern will repeat. But if it takes a very long time before the repetitions appear, then probably it would be sufficiently close to real randomness (Bostrom & Sandberg 38-39). Also, there might be random variations that are hidden to our observations, and thus would not be properly represented in the simulation. They recognize the profound difficulty in incorporating true randomness or hidden variables into the simulation. Yet they believe these sorts of randoms most likely will be unnecessary for whole brain emulation.

But perhaps there is more to consider. Lawrence Ward reviews findings that demonstrate neural noise is pink noise, or what is called 1/f noise. (Ward 145-153, citing research by Lundström and McQueen, and Novikov, Shannonhoff-Khalsa, Schwartz, and Wright) On account of its fractal nature, 1/f noises are always parts of similar larger-orders of variation happening on much longer time-scales. We might have to wait weeks or months to see larger-scale variations that were varying the randomness of the more local noisy events. (Anderson & Mandell 78-79) These are what Gregory Bateson calls metarandom variables. They are hidden to us, because we never see the whole picture (Bateson Steps to an Ecology 418). It’s why live lobsters never notice their cooking water gradually increase to boil (Mind and Nature 109). They only notices alterations on a local level, so nothing really seems to be changing. In a similar way, if all we are observing is randomness on a smaller scale, we might be missing the larger scale variations. It would be like randomly adjusting a radio to pick up different bands of radio static. If all we knew was the randomness of radio static at each moment, we might not also notice the higher order randomness that varies the lower one that we are listening-to. Because these uncontrollable unpredictabilities are essential to all the random changes happening around us, Bateson calls them wild variables. (Mind and Nature 49-50)

Perhaps it is for similar reasons that Benoit Mandelbrot classifies 1/f noise under what he terms “wild randomness” and “wild variation.” (Mandelbrot The (mis)Behavior of Markets 39-41) This sort of random might not be so easily simulated. Mandelbrot gives two reasons for this.

1) In wild randomness, there are events that defy the normal random distribution of the bell curve. He cites a number of stock market events that are astronomically improbable. But such events in fact happen quite frequently in natural systems despite their seeming impossibility. There is no way to predict when they will happen or how drastic they will be. (The (mis)Behavior of Markets 4)

2) Each event is random and yet it is not independent from the rest, like each toss of a coin is. One seemingly small anomalous event will echo like reverberations at unpredictable intervals into the future. (The (mis)Behavior of Markets 181-185)

For these reasons, he considers wild variation to be a qualitatively different state of indeterminism than the usual mild variations we encounter at the casino. For, there is infinite variance in the distributions of wild randomness. Anything can happen at any time (Mandelbrot, Fractals and Scaling 128). He says, “the fluctuation from one value to the next is limitless and frightening.” (Mandelbrot (mis)Behavior of Markets 39-41) This is the wildness of our brains.

Paul Shepard considers our minds to be wild in an even more literal sense: we are wild animals. He distinguishes tameness from domestication. Cows are domesticated. They have been bred to suit our needs. And now their genes would probably not prepare them to live in the wild without human protections. But the human species has merely been tamed by culture and not domesticated like cows. Genetically, we are still the same wild creatures who hunted the Pleistocene savannas. So to emulate the human brain is to simulate the workings not of a rational machine, but of a wild animal. (Shepard 132-133) He writes, “The savage mind is ours! ... as a species we have in us the call of the wild.” (143)

Shepard’s characterizes the wild, like Bateson and Mandelbrot do, as being too complex for any simulation. But he offers his own theory to explain why. He notes the fractal nature of reality. Within every scale is another smaller scale, and so on to infinity. He says that every layer of complexity operates according to deterministic principles. But, there is no lowest level of complexity. Hence there is no way to get to the bottom of what is happening now. It’s turtles all the way down. Thus there is no way to fully understand why things are the way they are now. And thus we can never know how things will be in the future. (146-147)


But let’s suppose that the brain’s wild randomness can be adequately simulated. Will brain emulation still attain its fullest success of perfectly replicating a specific person’s own identity? Bostrom & Sandberg recognize that neural noise will prevent precise one-to-one emulation. However, they think that the noise will not prevent the simulation from producing meaningful brain states (
Bostrom & Sandberg 7). But to pursue further the personal identity question, let’s imagine that we want to emulate a certain slot machine. A relevant property is its unpredictability. Consider these two possibilities. 1) We set the original and the simulation to the same starting position. We give both handles a number of pulls. Each time, they both show the same outcomes, because we replicated the mechanics perfectly. But then, we cannot say that we have preserved its relevant essential property of being unpredictable. For, we can just run the simulator by itself and that will predict the original’s future outcomes. Or, 2) instead the emulation produced its own different random series of outcomes. Then in fact we would be replicating the original’s property of unpredictability.

The problem is that the brain’s 1/f noise is wildly random. So suppose we emulate some person’s brain perfectly. And suppose further that the original person and her emulation have an identity merger where each one thinks they are talking to their very own selves when really they are talking to the other. They confuse themselves with one another. They are completely aware of what is in the other’s mind at that first moment, because they can tell it is the same as what is in their own mind. And suppose further that the original person loses her fear of death, knowing that something she cannot distinguish from himself will carry on after her body dies. But if both minds are subject to wild variations, then their consciousness and identity might come to differ more than just slightly. They could veer-off wildly. The original person and her emulation might become so mistrustful of each other, that they want to end the other’s existence.

So we might need to emulate this wild neural randomness. But that seems to remove the possibility that the emulation will continue on as the original person. Perhaps our very effort to emulate a specific human brain results in our producing an entirely different brain altogether.


[Next entry in this series.]


Anderson, Carl M. & Arnold J. Mandell. Fractal Time and the Foundations of Consciousness: Vertical Convergence of 1/fPhenomena from Ion Channels to Behavior States. in Fractals of Brain, Fractals of Mind. Ed. Earl Mac Cormac & Maxim I. Stamenov. Amsterdam: John Benjamins Publishing Company, 1996. More information and limited preview available at: http://books.google.be/books?id=WdERazd7Ik4C&hl=en


Bateson, Gregory. "Effects of Conscious Purpose on Human Adaptation." in Steps to an Ecology of Mind. London: Granada Publishing, 1972. . More information and limited preview available at: http://books.google.be/books?id=FQvfqk31zFQC&hl=en


Bateson, Gregory. Mind and Nature: A Necessary Unity. London: Fontana, 1979. More information available at: http://books.google.be/books?id=aQtHAAAAMAAJ&hl=en&pgis=1


Sandberg, A. & Bostrom, N. (2008): Whole Brain Emulation: A Roadmap, Technical Report #20083, Future of Humanity Institute, Oxford University. Available online at:http://www.fhi.ox.ac.uk/Reports/2008-3.pdf


Dartnall, Terry. "Introduction: On Having a Mind of Your Own." in Artificial Intelligence and Creativity: An Interdisciplinary Approach. Ed. Terry Dartnall. Dordrecht: Kluwer Academic Publishers, 1994. More information and limited preview available at: http://books.google.be/books?id=4phC9RwvC8YC&hl=en


Dennett, Daniel. Brainstorms. Hassocks: Harvester Press, 1978. More information available at: http://books.google.be/books?id=s3V-AAAAMAAJ&hl=en&pgis=1


Goertzel, Ben. Chaotic Logic: Language, Thought, and Reality from the Perspective of Complex Systems Science. London: Plenum Press, 1994. More information and limited preview available at: http://books.google.be/books?id=zVOWoXDunp8C&hl=en

Johnson-Laird, R. N. The Computer and the Mind: An Introduction to Cognitive Science. Cambridge: Harvard University Press, 1988. More information and limited preview available at: http://books.google.be/books?id=Tf5gRFgVuegC&hl=en


Johnson-Laird, Philip. Human and Machine Thinking. London: Lawrence Erlbaum Associates, Publishers, 1993. More information and limited preview available at: http://books.google.be/books?id=sPbdQjtkIhkC&hl=en


Mandelbrot, Benoit B., & Richard L. Hudson. The (mis)Behavior of Markets: A Fractal View of Risk, Ruin, and Reward. New York: Basic Books, 2004. More information available at: http://books.google.be/books?id=DPwBTj99a7UC&hl=en


Science Daily. "Mysterious 'Neural Noise' Actually Primes Brain For Peak Performance." Nov. 13, 2006. Available online at: http://www.sciencedaily.com/releases/2006/11/061112094812.htm


Shepard, Paul. Coming Home to the Pleistocene. Washington, D.C.: Island Press, 1998. More information and limited preview available at: http://books.google.be/books?id=5b18NqLB8LMC&hl=en


Ward, Lawrence M. Dynamical Cognitive Science. London: MIT Press, 2002. More information and limited preview available at: http://books.google.be/books?id=g1ZMAoWGYesC&hl=en


Also mentioned:

(Lundström and McQueen, 1974, "A proposed 1/f noise mechanism in nerve cell membranes," Journal of Theoretical Biology, 45, 405-409).


(Novikov E., A. Novikov, Shannonhoff-Khalsa, Schwartz, and Wright, 1997, "Scale-similar activity in the brain," Physical Review E, 56, R2387-R2389,)



12 Jun 2009

The Wheel is Come Full Pixel: Analog against Digital; Bostrom and Sandberg's Brain Emulation, Examined and Critiqued. Section 4


by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

[Central Entry Directory]
[Posthumanism, Entry Directory]
[Other entries in this paper series.]

[The following is tentative material for my presentation at the Society for Philosophy & Technology Conference this summer.]


[Other entries in this series.]



Corry Shores


Do Posthumanists Dream of Pixilated Sheep?

Bostrom and Sandberg's Brain Emulation,

Examined and Critiqued


Section 4:


The Wheel is Come Full Pixel:

Analog against Digital



Digital technologies replaced analog ones. These two sorts of quantity-representation reside in contrary worlds: the continuous versus the discrete. An abacus is digital. It computes one discrete value or another, but not the ones in between. When we count to two on our fingers, meaningless empty space spans between our digits. So spreading our fingers further apart does not change their value. Slide-rules, however, are analog. One ruler slides against another continuously. So it may calculate any possible real number value along the continuum. It could potentially compute and display irrational numbers like pi or the golden number. However, a digital computer attempting this would never cease carrying-over into the next digit places. So in a sense, analog computers have more computing potential for certain applications. In fact, Hava Siegleman argues that analog is capable of a hyper-computation that no digital computer could possibly accomplish. (Siegleman 109)

Nelson Goodman’s oft cited terminology clarifies the difference. He distinguishes density from differentiation, and continuity from discretion. Analogical values are placed along a continuous scale. Between any two values is a third: this is its density. It implies that all readings are approximations. For, there can be no pinpoint determination, but instead just more-and-more precise possible readings. Digital, however, uses discrete units, and thus each value is perfectly differentiated from the others (Goodman 160-161).

According to James Moor,

in a digital computer information is represented by discrete elements and the computer progresses through a series of discrete states. In an analogue computer information is represented by continuous quantities and the computer processes information continuously. (Moor 217)

Our emulated brain will receive simulated sense-signals. Does it matter if they are digital rather than analog? Many audiophiles swear by the unsurpassable superiority of analog. It might be less precise, but it is always like natural sound waves. Digital, even as it becomes more accurate, still sounds to them artificial or cartoon-like. In other words, there might be a qualitative difference to how we experience analog and digital stimuli, even though it might take a person with extra sensitivities to bring this difference to our explicit awareness.

And if the continuous and discrete are such polar realities, then perhaps a brain computing in analog would experience a qualitatively different feel of consciousness than if the brain were instead computing in digital.

A relevant property of an audiophile’s brain is its ability to discern analog from digital, and prefer one to the other. But a digital emulation of the audiophile’s brain might not be able to share its appreciation for analog. And perhaps digital emulations might even produce a mental awareness quite foreign to what humans normally experience.

Bostrom’s & Sandberg’s brain emulation exclusively uses digital computation. But they acknowledge that some argue that analog and digital are qualitatively different. And the authors even admit that implementing analog in brain emulation could present profound difficulties. (39) But there is no need to worry, they think. And they give their reasons why the qualitative difference is irrelevant.

They first argue that brains are made of discrete atoms. These must obey quantum mechanical rules that force the atoms into discrete energy states. Moreover, these states could be limited by a discrete time-space. (38) The debate over whether or not the world is continuously divisible spans back at least to Zeno of Elea. Perhaps quantum physics finally settled this issue, at least as far as it concerns us here. I apologize that I am unable to comprehend whether and how this might be so. Let’s presume it is. I am still uncertain that digital technologies will be able to compute such tiny quantum-scale variations. This is where analog now already has the edge.

Yet their next argument calls even that notion into question as well. They make what is called “the argument from noise.” Analog devices always take some physical form. It is unavoidable that interferences and irregularities, called noise, will make the analog device imprecise. So analog might be capable of taking-on an infinite range of variations. However, it will never be absolutely accurate, because noise always causes it to veer-off slightly from where it should be. Yet digital has its own inaccuracies. It is always missing variables between its discrete values. Nonetheless, digital is improving. Little-by-little it is coming to handle more variables. It is filling in its gaps. Digital will never be completely dense like analog. But, soon the span between its gaps will equal the range that analog veers-off from its proper values. Digital’s blind-spots and analog’s drunken swerve will miss the same range of variation. So, we only need to wait for digital technology to improve enough that it can compute the same values with equivalent precision. Both will be equally inaccurate, but each for its own reason.

But perhaps the argument from noise reduces the analog/digital distinction to a quantitative difference rather than a qualitative one. And analog is so prevalent in neural functioning that we should not so quickly brush it off.

First note that our nervous system’s electrical signals are discrete pulses, like Morse code. In that sense they are digital. However, the frequency of the pulses can vary continuously (Jackendoff 33). For, the interval between two impulses can take any value. (Müller et al. 5b)

This applies as well to our sense signals. As the stimulus varies continuously, the signal’s frequency and voltage changes proportionally. (Marieb & Hoehn 401) Recent research suggests that the signal’s amplitude is also graded and hence is analog. (McCormick et.al, abstract) Also consider that our brains learn by adjusting the weight or computational significance of certain signal channels. A neuron’s signal inputs are summed. When it reaches a specific threshold, the neuron fires its own signal. It then travels to other neurons where the process is repeated. Another way the neurons adapt is by altering this input threshold. Both these adjustments may take on a continuous range of values. Hence analog computation is fundamental to learning (Mead 353-354)

Fred Dretske gives reason to believe that our memories store information in analog. We may watch the setting sun and observe intently as it finally passes below the horizon. Yet, we do not know that the sun has set until we convert the fluid continuum of sense impressions into concepts. These are discrete units of information, and are thus digital. (Dretske 142) Yet we might later find ourselves in a situation where it is relevant to determine what we were doing just before the sun completely set. To make this assessment, we would need to recall our experience of the event, and re-adjust our sensitivities for a new determination, or as Dretske writes, “as the needs, purposes, and circumstances of an organism change, it becomes necessary to alter the characteristics of the digital converter so as to exploit more, or different, pieces of information embedded in the sensory structures.” (Dretske 143) So in other words, because we can always go back into our memories to make more and more precise determinations, we must somehow be recording sense data in analog, Dretske argues.

Bostrom & Sandberg make another computational assumption. They argue that no matter what the brain computes, a digital (Turing) computer could theoretically accomplish the same operation. (Bostrom & Sandberg 7) But note that we are emulating the brain’s dynamics. And according to Terence Horgan, such dynamic systems use “continuous mathematics rather than discrete.” (Horgan 19)

It is for this reason that Whit Schonbein claims analog neural networks would have more computational power than digital computers. (Schonbein 61) The values in continuous systems make use of "infinitely precise values" that can "differ by an arbitrarily small degree." (Schonbein 60d) And yet, like Bostrom & Sandberg, Schonbein critiques analog using the argument from noise. He says that analog computers are more powerful only in theory. As soon as we build them, noise from the physical environment diminishes their accuracy. (65-66) Curiously, he concludes that we should not for that reason dismiss analog. He says that analog neural networks, “while not offering greater computational power, may nonetheless offer something else.” But he leaves it for another effort to say exactly what the unique value of analog computation would be. (68cd)

A.F. Murray’s research on neural-network learning supplies an answer. Analog noise interference is significantly more effective than digital at aiding adaptation (Murray 1547). Being "wrong" allows neurons to explore new possibilities for weights and connections. This enables us to learn and adapt to a chaotically changing environment. Using digitally-simulated neural noise might be inadequate. Analog is better. For, it affords our neurons an infinite array of alternate configurations (1547-1548). Hence in response to Bostrom’s & Sandberg’s argument from noise, I propose the argument for noise.



[Next entry in this series.]


Dretske, Fred. Knowledge and the Flow of Information.Cambridge: MIT Press, 1981. More information at: http://books.google.be/books?id=IlAtGwAACAAJ&hl=en


Goodman, Nelson. Languages of Art, An Approach to a Theory of Symbols. New York: The Bobb’s-Merrill Company, 1968. More information and preview available at: http://books.google.be/books?id=e4a5-ItuU1oC&printsec=frontcover&dq=Languages+of+Art,+An+Approach+to+a+Theory+of+Symbols&ei=UIcySoXfIJbyygT81JWqBg&hl=en


Horgan, Terence. “Connectionism and the Philosophical Foundations of Cognitive Science.” in Metaphilosophy. Vol. 28, Nos. 1 & 2, January/April 1997, pp.1-30. Available online at: http://www3.interscience.wiley.com/journal/119168156/abstract?CRETRY=1&SRETRY=0


Jackendoff, Ray. Consciousness and the Computational Mind. London: MIT Press, 1987. More information at: http://books.google.be/books?id=ICEpAAAACAAJ&hl=en


Marieb, Elaine N., & Katja Hoehn. Human Anatomy & Physiology. London: Pearson, 2007. More information at: http://books.google.be/books?id=yOm1LXhEX40C&hl=en


McCormick, David A., Yousheng Shu, Andrea Hasenstaub, Alvaro Duque, & Yuguo Yu. "Modulation of intracortical synaptic potentials by presynaptic somatic membrane potential." Nature 441, 761-765 (8 June 2006), Published online 12 April 2006. Text available online at: http://www.nature.com/nature/journal/v441/n7094/full/nature04720.html


Mead, Carver. Analog VLSI and Neural Systems. Amsterdam: Addison-Wesley Publishing Company, 1989. More information available at: http://books.google.be/books?id=nr4HAAAACAAJ&hl=en


Moor, James H.. “Three Myths of Computer Science.” The British Journal for the Philosophy of Science, Vol. 29, No. 3, Sep., 1978. Text available online at: http://www.jstor.org/sici?sici=0007-0882(197809)29:32.0.CO;2-6


Müller, Berndt, & Joachim Reinhardt, Michael Thomas Strickland. Neural Networks: An Introduction. Berlin: Springer, 1995.

More information and preview available at: http://books.google.be/books?id=EFUzMYjOXk8C&hl=en


Sandberg, A. & Bostrom, N. (2008): Whole Brain Emulation: A Roadmap, Technical Report #20083, Future of Humanity Institute, Oxford University. Available online at: http://www.fhi.ox.ac.uk/Reports/2008-3.pdf


Siegelmann, Hava T. “Neural and Super-Turing Computing.” Minds and Machines. Vol. 13, Issue 1, February 2003. Available online at: http://www.springerlink.com/content/j7l1675237505m16/


Schonbein, Whit. "Cognition and the Power of Continuous Dynamical Systems." Mind and Machines, Springer, (2005) 15: pp. 57-71. More information at: http://www.springerlink.com/content/xtx321861761117r/?p=91ba33f01d0a4099b74dcad02b1a5860π=2


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