It is the ability of the brain to simultaneously process incoming stimuli.
This becomes most important in vision, as the brain divides what it sees into four components: color, motion, form, and depth. These are individually analysed and then compared to stored memories, which helps the brain identify what you are viewing.
The brain then combines all of these into one image that you see and comprehend. This is a continual and seamless operation. The advantage of parallel processing is that it allows the brain to simultaneously identify different stimuli and allow for quick and decisive action.
This is one of the reasons that the human brain is much more powerful than the computer. While a computer is a million times faster than a human's neural network, it is the fact that we have a large number of processors compared to computers.
As Donald Hoffman said (1998, p.xiii) "You can buy a chess machine that beats a master but can't yet buy a vision machine that beats a toddler's vision." The technology known as computer vision, however, allows computers to recognize objects visually.
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