Feedback = 雞 與 蛋

雞 與 蛋 and feedback seem like unrelated, but take a look at the following diagram, you will understand the similarity of the concept.

Microphone and Speaker

If you ask chicken first or egg first, you can also ask microphone starts the tone first or the speaker starts the tone first. We all know that when we put the microphone close to the speaker, a load tone is generated from nowhere because of the feedback. This feedback in technical term is called “positive feedback" because output generates input and input generates output. Which started first, no one knows.

A term called “negative feedback" is applied to the case when the feedback from the output to the input is used to correct the output, such as “constructivie criticism", the system will adjust and correct any mistake. This is the main concept in feedback control. Therefore we cannot say whether “feedback" is good or bad, it depends on the situation.

A person is a system, if he knows that criticism is good for him, he as a system can improve. The only problem is that a person cannot tell the difference between “positive" or “negative" when he receives the “feedback".

Take measuring blood pressure for example. A lot of people know how to take blood pressure measurement but do not understand what and why. The following diagram explains what is blood pressure.

Blood Pressure Measuring

Heart is the blood pressure generator, each heart beat pumps the blood to circulate. Each beat is like a drop of a rock in the pond and the beat or wave moves throughout the blood vessel. Pressure should be different at different part of the vessel depending on how easy the blood can get through. Blood pressure to the artery wall if the through pressure meet the resistance such as clog or vessel narrowed. This is indicating what doctor said, “hypertension" or “high blood pressure".

If you know you have high blood pressure, you get tensed, stressed and your blood vessel tightened, your blood pressure will get even higher. This is the “positive feedback" effect. Try relax and take it easy and deal with it with “negative feedback", a correct or corrective way.