I'm a fan of the cognitive sciences. I enjoy reading books about
neuroscience, AI, neural networks, and psychology. I read the books for
the pure pleasure of expanding my understanding; stretching your mind
(especially about minds) is very entertaining!
My latest excursion on this front was Jeff Hawkins's new book,
On Intelligence.
Hawkins is best known as the founder of PalmPilot, Handspring
and the inventor of the Graffiti alphabet. But he's also a brain freak!
Apparently, he's been reading the literature for most of his adult life.
He runs a research facility called the Redwood Neurosciences Institute.
On Intelligence has a
very ambitious aim: to provide the long-missing
framework that explains intelligence in terms of neural organization and
functioning.
Hawkins's theory is really a theory of how the neocortex works; the author
largely dismisses the contributions of the 'primitive' brain to
intelligence. The gist of the theory is that the neocortex implements a
hierarchical memory-prediction machine; it tries to predict the future based
on the patterns it has stored (memory). As sensory input flows up into the
various layers of the cortex, the cortex tries to match the input to
previously seen patterns. Matched patterns at lower levels create
abstractions to be used by higher levels. The flow of information proceeds
not just up, but down the hierarchy: when a pattern matches, lower levels
are biased about what to expect next. Hawkins makes heavy use of the
anatomical fact that there are more 'down' pathways than 'up' pathways to
support this argument. Information is processed into higher and higher
abstractions as the signals propagate upward, predictive information
trickles downward as a result.
The definition of intelligence, according to Hawkins, is the ability to
predict the future based on the world-model you have built in your
neocortex. This contrasts to Turing's behavior-based definition of intelligence, as defined by the Turing Test. Hawkins notes, correctly I think, that intelligence can exist without behavior (as during navel-gazing sessions).
Though oversimplified (by his own admission), I found this to be the most
tractable theory of cognition I have ever read. I whole-heartedly
recommend the book for its mind-stretching description of our minds.
Now, onto a small criticism. At one point in his book, Hawkins gives a
approving nod to John Searle for his famous 'Chinese Room' criticism of AI.
For some background on this argument, see this
Wikipedia entry.
I disagree
with Searle's arguments; and I was
very surprised that Hawkins agreed,
especially given his arguments throughout his book. The "Systems Reply",
in my opinion, is the best counter argument. It says that the person in
the room doesn't understand Chinese, but the combination of the book, the
person and the reams of scratch paper, taken as a whole, understand
Chinese.
Consider what it really takes to answer questions about a story: the
ability to recognize not just words, but their meaning. And not just the
meaning in a dictionary-lookup sense, but rather the ability to compare the
narrative to your internal model of the world. The simple linear stream of
words builds in the reader an enormous model, a
predictive model, of the
world in the story; a model based on the reader's own world model.
I suggest that the book needs to contain an entire memory-prediction
hierarchy, an entire world model of some sophistication, in order to answer
questions about the story. There can be no intelligent commentary on the
story without the predictive richness of a mind. Searle misleads us into
thinking that the book, the program, is a slim volume that only implements
a translation algorithm. The book needs to be
enormous, essentially
capturing the representational richness of the neocortex. Perhaps the book
would have to be a detailed map of the relevant neuronal structures -- like
in "A Conversation with Einstein's Brain" in "Godel, Esher, Bach" by
Hofstadter.
If the Chinese Room, as a whole, implements a (to use Hawkins's term)
memory-prediction hierarchy, then it is capable of
really understanding
Chinese. Case closed.
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