The difference between brains and computers

I believe that within my lifetime processors will get powerful enough and software good enough that we will see computers that emulate human brains and pass the Turing Test (for more detail see my earlier posts Kurzweil predicts we will reverse engineer the human brain using software, Kurzweil predicts computers with the power of the human brain by 2025, Scientists create artificial brain with 2.3m simulated neurons).

Today I read a good Economist article which explains the challenges of building ‘human computers’. Brains currently have three key characteristics that computers do not:

These are: low power consumption (human brains use about 20 watts, whereas the supercomputers currently used to try to simulate them need megawatts); fault tolerance (losing just one transistor can wreck a microprocessor, but brains lose neurons all the time); and a lack of need to be programmed (brains learn and change spontaneously as they interact with the world, instead of following the fixed paths and branches of a predetermined algorithm).

Having identified these characteristics scientists are now working to design around them, as detailed in the rest of the Economist article. In summary progress is being made but it is very early days. The third characteristic of not needing to be programmed runs contrary to our current notions of development, and is perhaps the most challenging.

The other issue at play here is consciousness. ‘Would human computers be conscious or not?’ and ‘What is consciousness anyway?’ are unresolved questions with inherently unknowable answers. My view is that consciousness arises from the mind and human computers would be to all intents and purposes be conscious. Any other answer creates more questions than it answers and hence falls foul of Occam’s razor. This question was debated earlier today here and on Hacker News.