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GenericThinker comments on Hard Takeoff - Less Wrong

14 Post author: Eliezer_Yudkowsky 02 December 2008 08:44PM

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Comment author: GenericThinker 03 December 2008 03:17:29AM -1 points [-]

"But the much-vaunted "massive parallelism" of the human brain, is, I suspect, mostly cache lookups to make up for the sheer awkwardness of the brain's serial slowness - if your computer ran at 200Hz, you'd have to resort to all sorts of absurdly massive parallelism to get anything done in realtime. I suspect that, if correctly designed, a midsize computer cluster would be able to get high-grade thinking done at a serial speed much faster than human, even if the total parallel computing power was less."

That is just patently false, the brain is massively parallel and the parallelism is not cache look-ups it would be more like current GPUs. The computational estimate does not take into account for why the brain has as much computational power as it does ~10^15 or more. When you talk about relative speed what you have to remember is that we are tied to our perception of time which is roughly between 30-60FPS. Having speeds beyond 200Hz isn't necessary since the brain doesn't have RAM or caches like a traditional computer to store solutions in advance in the same way. By having the speed at 200Hz the brain can run fast enough to give us real-time perceptions while having time to do multi-step operations. A nice thing would be if we could think about multiple things in parallel the way a computer with multiple processors can focus on more then one application at the same time.

I think all these discussions of the brains speed are fundamentally misguided, and show lack of understanding of current neuroscience computational or otherwise. Since to say run the brain at 2Ghz what would that mean? How would that work with our sensory systems? If you only have one processing element with only 6-12 functional units then 2Ghz is nice if you have billions of little processors and your senses all run around 30-60FPS then 200Hz is just fine without being overkill unless your algorithms require more then 100 serial steps. My guess would be that brain does a form of parallel algorithms to process information to limit that possibility.

On the issue of mental processing power look at savants, some of them can count in primes all day long or can recite a million digits of pi. For some reason the disfunction in their brains allows them to tap into all sorts of computational power. The big issue with the brain is that we cannot focus on multiple things and the way in which we perform for example math is not nearly as streamlined as a computer. For may own part I am at my limit multiplying a 3 digit number by a 3 digit number in my head. This is of course a function of many things but it is in part a function of the limitations of short term memory and the way in which our brains allow us to do math.