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Book Summary InformationAuthor: Jeff Hawkins, Sandra Blakeslee Edition: Hardcover Format: Bargain Price Published: 2004-10-03 ISBN: N/A Number of pages: 272 Publisher: Times Books
Book Reviews of On IntelligenceBook Review: A Common Cortical Algorithm Summary: 4 Stars
In "On Intelligence," Jeff Hawkins presents a new theory about how the brain works and how we can finally build "intelligent" machines. The neocortex, the center of higher thought, is the focus of attention here. Hawkins says that neuroscientists are lost in the complexity of mapping out neural pathways, and are not coming up with compelling overarching theories that begin to explain how we think and learn.
He believes there is enough evidence now to posit a common cortical algorithm, as first proposed by Vernon Mountcastle, a neuroscientist at Johns Hopkins, in 1978. The algorithm is hierarchical, with lower layers encoding data from a sensory organ, but higher layers dealing with abstract signals that bear little resemblance to the sensory signals. Hawkins asserts that brain researchers got sidetracked partly due to the experimental difficulty of taking measurements. The standard approach is to present a static sensory stimulus and take readings of resulting cortex activity. It is too difficult to work with dynamically changing stimuli, so researchers have missed a point that Hawkins believes is crucial: the brain can only perceive dynamic stimuli.
Hawkins' theory, called "Memory Prediction Framework," defines intelligence as "the capacity of the brain to predict the future by analogy to the past." According to him, there are four key attributes of neocortical memory that differ from computer memory:
* All memories are inherently sequential.
* Memory is auto-associative; a partial memory can be used to retrieve the full memory.
* Memories are stored in invariant representations.
* Patterns are stored in a hierarchy.
Support for the theory is most concretely expressed in chapter six, the meatiest part of the book. This is where the author describes in some detail his vision of how the neural circuitry in the layers of cortex works. The description is compelling, but takes more work to follow than the other chapters.
Chapter six ends with several fascinating observations that are built on top of the neural circuitry described earlier. It emphasizes that perception and behaviour are highly interdependent because they both originate in a detail-invariant representation that is then transmitted through both motor and sensory cortex. Also, although many researchers have discounted it, Hawkins argues that feedback and the importance of distant synapses in cortex is essential to explain the Memory Prediction Framework theory, and should be reconsidered. The theory includes the broad principles of how hierarchical learning of sequences explains how children first learn letters, then words, phrases and finally sentences, and as adults we can speed-read without needing to study every letter. The author believes that the memory of sequences re-forms lower and lower in cortex, allowing higher layers to learn more complex patterns. Finally, the hippocampus is briefly described as logically residing at the top of the cortical hierarchy: the short-term repository of new memories.
An impressive result of the speculations in chapter six is a list in the appendix of 11 specific, testable predictions made by the theory, which is an invitation to brain researchers. And Hawkins founded a company, Numenta, to develop the Hierarchical Temporal Memory concept based on the theory.
Chapter six also hints at how daydreaming or imagining occurs, when predictions from layer 6 of a cortical column are fed back to layer 4 of the same column. Cortical modeller Stephan Grossberg calls this "folded feedback". In chapter seven the book expands on philosophical speculation about the origin of consciousness and creativity that arise from the Memory Prediction Framework theory. Creativity is defined here as "making predictions by analogy". As the author says, there is a continuum of creativity, from mundane extrapolations from learned sequences in sensory cortex to rare acts of genius. But they have a common origin. This is how a piano player can quickly figure out how to play simple melodies on a vibraphone, or a customer in a strange restaurant can figure out that there is probably a restroom in the back. Creativity is so pervasive that we hardly label it as such, unless it violates our predictions like an unusual work of art. There are practical suggestions in this section for how to train oneself to be more creative, and an interesting story of how Hawkins conceived the handwriting recognition system, Graffiti.
Chapter seven ends in speculation about the nature of consciousness, imagination and reality in response to the inevitable questions to which this type of work gives rise. A review on the Amazon website by Dr. Jonathan Dolhenty takes issue with what he describes as "plain old-fashioned metaphysical materialism and, probably, old-school psychological behaviourism," which are largely discounted theories today. Dolhenty is a philosopher who thinks human intellect at the higher abstract and conceptual levels cannot be described by such a simple extrapolation of the Memory Prediction Framework. But I found the connections made between brain theory and "mind" reassuring. Leave it to others to build on this foundation. In fact, Hawkins does hint at a broader source of the mind in chapter seven, where he says that it is influenced by the emotional systems of the old brain and by the complexity of the human body.
The last chapter in the book contains another vision, of how intelligent machines might be built in the future. This is back into the Popular Science mode. Unlike many current roboticists who believe humanoid robots will be needed to interact with humans, Hawkins believes humanoid form is pointless and impractical. He advocates working from inside out, by building sensing mechanisms and attaching them to a hierarchical memory system that works on cortex principles. Then by training the system he believes it will develop its own representations of the world. This system can be built into any sort of machine, and the sensors can be distributed if desirable.
The technical challenges of building an intelligent machine include capacity, which by analogy to the brain, at 2 bits per synapse, would require 8 trillion bytes of memory or about 80 hard drives. Connectivity is a larger problem, since it would be impossible to provide dedicated connections. Hawkins believes the answer would be some sort of shared connections, like in today's phone network, but this is still a challenge.
As an aside, there is no mention of the Cyc project, which has been working since 1984 to build a mammoth semantic knowledge base. But unlike the automatically learned representations in Hawkins' proposed artificial brain, the ones in Cyc are hand-input in a preconceived structure as a vast quantity of terms related by assertions.
The last chapter ends with a very positive view of the potential of intelligent machines to solve problems humans cannot, because they can be equipped with custom senses, immense memory, and even be networked to form hierarchies of intelligent machines. Hawkins believes that intelligent machines will be a hot topic in the next ten years. It is easy to get caught up in his excitement.
Summary of On IntelligenceFrom the inventor of the PalmPilot comes a new and compelling theory of intelligence, brain function, and the future of intelligent machines Jeff Hawkins, the man who created the PalmPilot, Treo smart phone, and other handheld devices, has reshaped our relationship to computers. Now he stands ready to revolutionize both neuroscience and computing in one stroke, with a new understanding of intelligence itself.
Hawkins develops a powerful theory of how the human brain works, explaining why computers are not intelligent and how, based on this new theory, we can finally build intelligent machines.
The brain is not a computer, but a memory system that stores experiences in a way that reflects the true structure of the world, remembering sequences of events and their nested relationships and making predictions based on those memories. It is this memory-prediction system that forms the basis of intelligence, perception, creativity, and even consciousness.
In an engaging style that will captivate audiences from the merely curious to the professional scientist, Hawkins shows how a clear understanding of how the brain works will make it possible for us to build intelligent machines, in silicon, that will exceed our human ability in surprising ways.
Written with acclaimed science writer Sandra Blakeslee, On Intelligence promises to completely transfigure the possibilities of the technology age. It is a landmark book in its scope and clarity.
Jeff Hawkins, the high-tech success story behind PalmPilots and the Redwood Neuroscience Institute, does a lot of thinking about thinking. In On Intelligence Hawkins juxtaposes his two loves--computers and brains--to examine the real future of artificial intelligence. In doing so, he unites two fields of study that have been moving uneasily toward one another for at least two decades. Most people think that computers are getting smarter, and that maybe someday, they'll be as smart as we humans are. But Hawkins explains why the way we build computers today won't take us down that path. He shows, using nicely accessible examples, that our brains are memory-driven systems that use our five senses and our perception of time, space, and consciousness in a way that's totally unlike the relatively simple structures of even the most complex computer chip. Readers who gobbled up Ray Kurzweil's (The Age of Spiritual Machines and Steven Johnson's Mind Wide Open will find more intriguing food for thought here. Hawkins does a good job of outlining current brain research for a general audience, and his enthusiasm for brains is surprisingly contagious. --Therese Littleton
Neural Networks Books
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