Thursday, January 9, 2014

Comment and quotes on brain

it performs massively parallel computations extremely efficiently. For example, complex visual perception occurs within less than 100 ms, that is, 10 processing steps!link

A human can perform significant tasks in much less time than a second. For example, I could show you a photograph and ask you to determine if there is cat in the image. Your job would be to push a button if there is a cat, but not if you see a bear or a warthog or a turnip. This task is difficult or impossible for a computer to perform today, yet a human can do it reliably in half a second or less. But neurons are slow, so in that half a second, the information entering your brain can only traverse a chain one hundred neurons long. That is, the brain 'computes' solutions to problems like this in one hundred steps or fewer, regardless of how many total neurons might be involved. From the time light enters your eye to the time you press the button, a chain no longer than one hundred neurons could be involved. A digital computer attempting to solve the same problem would take billions of steps. One hundred computer instructions are barely enough to move a single character on the computer's display, let alone do something interesting.-Jeff Hawkings, On intelligence
Unlike traditional computer architectures which have extremely high clock rates and can perform deep loops in short order with billions of instructions per second serially, allowing for billions of steps to be taken in an algorithm. The brain has to do its processing with about 100 instructions per second serially. Given this slow speed, it requires a very different kind of algorithms that are massively parallel and can work within few steps. That is not all kinds of algorithms are viable or can be performed within a few dozen steps.

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