Unnaturally Long Attention Span

AvatarA blog about Grad School at Stanford, Working in a Silicon Valley Internet Company, and Statistical Machine Learning. mike AT ai.stanford.edu

The Automatic Brain

Have you ever driven to work, or walked to class and later had no memory of how you actually got there? Have you ever really needed to study for a test, but just found it impossible to concentrate, no matter what you tried? One theory that can explain this seemingly irrationality is that there is a second brain, a parallel brain, which operates below the observable threshold of consciousness. This is the primitive brain, whose structure we share with other animals.

This primitive brain has a much larger memory capacity. In contrast, the conscious brain has a rather limited memory; studies have shown that people generally can only keep about 7 numbers in our heads. That is why phone numbers in the US have that length.

Some would argue that this subconscious brain is what distinguishes people from each other mentally. This is what some people would define as experience. Observe the people’s reasoning and rationalization patterns. Are they all that different? If they were, we would not be able to hold a logical discussion. It is the primitive brain that distinguishes two people.

But what distinguishes humans’ and machines’ "brains"? Machines have an enormouse advantage over the conscious "reasoning" brain. A machine can store much more than 7 items in short-term memory. Also, the execution speed of sequential reasoning operations in a machine is much faster than in a human’s conscious brain. This is because human brain circuits are limited in their operation by chemical "neurotransmitters" that are physically bound by diffusion speed. Therefore latency of information transfer in humans is higher.

Humans are no match for machines in what you might consider the highest form of human ability, "logical reasoning." In fact there are many well-known efficient algorithms for performing this process.

However, humans do have advantages over machines. The advantage is in this primitive, animal brain. This subconscious brain has massive parallelism, which allow data storage and computation to happen simultanesouly across all circuits. This tradeoff of latency for massive bandwidth have allowed humans to outperform computers in most interesting tasks.

This advantage may be only temporary, however. Although the machines were initially designed for sequential execution, recently we have seen more and more growth in developing parallel computation. Large data-intensive parallel systems have been developed. Parallel hardware and parallel algorithms have allowed new types of programs, such as entire-genome mappers, world-champion chess programs, and search engines. Human brain evolution is relatively fixed. Machine brain evolution seems to be exponential. The cross-over point will be where amazing things start to happen.

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