Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
Cybernetics is the science of control and communication.
Cybernetics was born out of the passion and excitement generated by the spread of complex mechanical and electrical machines, whose functioning was largely based on control processes. Cybernetics found similarities between some of those mechanical processes and some biological processes.
The concepts introduced by cybernetics built a bridge between machines and nature, between "artificial" systems and natural systems. For example, most machines employ one type of “feedback” or another. Feedback, by sending back the output as input, helps control the proper functioning of the machine.
The self-regulatory character of the human nervous system had been emphasized since the 1920s by the Russian physiologist Nikolai Bernstein. He concluded that, given the complexity of the human motor system, movement could not possibly be "commanded" by a central processor. Instead, he thought that movement was achieved by continually analyzing sensory inputs and adjusting motor output consequently. When I extend the arm to grab something, I have not computed exactly the trajectory and speed of my movement. I am re-computing it every second as my arm approaches the object. There is no computer in the brain that calculates the exact trajectory for the arm and the hand and the fingers in order to reach the glass. There is a continuous dialogue between the senses and the arm, the hand and the fingers, so that the trajectory is adjusted as motion proceeds. Both machines and living beings rely on “control systems”.
“Negative” feedback occurs when the output of the engine is fed back into the engine for the purpose of "controlling" it. For example, every engine has a valve that helps stabilize its power: the valve opens or closes depending on whether the engine is working too little or too much. The resulting power is always the same because the valve "balances" the work of the engine. The valve does so by opening or closing in a manner that depends on the work of the engine: in other words, the output of the engine is used to determine how much of the output of the engine has to be curtailed. This is negative feedback because the valve operates "against" the engine: it reverses the trend of the engine. The valve is canceling the fluctuations in the work of the engine.
“Positive” feedback occurs when those fluctuations are amplified, not canceled. The output of the engine is fed back into the engine for the purpose of reinforcing it. Instead of a stable output, we get runaway acceleration or complete rest, because positive feedback increases a perturbation instead of curbing it. Needless to say, positive feedback is not often used by engineers, who are more interested in building stable machines, rather than machines that rapidly self-destroy. But positive feedback is common in nature, where it determines the size of a population (until negative feedback prevails in the form of limited resources) and aggressive behavior (until negative feedback prevails in the form of a stronger opponent).
In human societies positive feedback is not rare. For example, positive feedback is often responsible for bestsellers: a record will sell more once it enters the best-selling charts and it will keep getting more popular for the simple reason that it is popular.
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