They might not look much like each other, but at first blush computers have several similarities with brains. For one thing, they can store information, just the same as our gray matter. For another, computers too have memory, though their use of memory is a bit different from ours, and their idea of "bad" memory is far different from ours as well. (It would be nice if we could simply swap out our bad memories in the same way a computer just needs a new memory module to be swapped in whenever bad memory arises.) In a sense, a computer's memory, depending on the type -- for example, RAM -- also "forgets" things when it releases information it no longer needs. Their forgetting is a bit more purposeful than ours, however. We don't plan to lose our car keys, wallets and remote controls.
Next, computers can process a whole lot of information, really fast. Relatively speaking, we can too. (Though for sheer, absolute number-crunching speed we can't possibly outperform computers with just our naked brains.)
Once we get past the storage, memory and processing similarities, though, the comparison begins to take on water. Beyond the superficial resemblances, the two aren't really much alike. The human brain can innovate -- humans can come up with ideas from out of the proverbial clear-blue sky. We're free thinkers, and self aware. Computers, though, must follow sets of instructions to accomplish tasks. They can't do anything they haven't already been given the tools, or information, to accomplish. These tasks may be complex and might otherwise take a human being thousands of years to complete, but the computer isn't able to jump outside the relatively narrow list of instructions it receives. While there have been great strides in artificial intelligence, computers are still a long way from replicating the human brain.
The numbers don't help with the comparison either. The human brain has an estimated storage capacity of some 2.5 petabytes of information (two and a half million gigabytes) -- not exactly the kind of storage you'll see in a single computer at your local box store outlet [source: Reber].
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