Positive and Negative Feedback – Concept and Examples

We explain what positive and negative feedback are, the characteristics of each one and examples. Also, what is homeostasis.

Positive and negative feedback
Feedback is a way of controlling a process, evaluating the results.

What are positive and negative feedback?

Broadly speaking, feedback is the mechanism through which the results of a process or an activity are reinserted into the system that produces it, to provide you with useful information when making decisions. In other words, it is a way of controlling a process, evaluating its results to see if it works more or less as expected.

The concept of feedback is used in very different fields, ranging from biology and physiology to the arts and techniques. In general, it is a “loop” or “return”, that is, a dynamic in which a part of the result is redirected to the process itself.

That is, the two possible types of feedback lead to different scenarios:

  • Negative feedback has a stabilizing effect on the system. It returns the information produced to the issuer, so that it can correct the input pattern, and thus keeps the system working. This is what happens, for example, with the quality control systems of factories: a portion of the manufactured products do not go on sale, but are consumed internally to ensure that they meet minimum quality standards.
  • Positive feedback has a creative, productive, and change-pushing effect. That is, it tends to increase the signal or activity, since by returning the information at the beginning, it enhances certain changes in the process. An example of this is the reinvestment of capital from a factory, in which the money obtained from the sale of products is spent on new machines that allow more products to be manufactured, in order to obtain more money and be able to improve the machines again.

See also: Interdependence

Examples of positive and negative feedback

Having understood the difference between positive and negative feedback, we can find other examples for each:

Examples of negative feedback:

  • The refrigerator thermostat, which measures the temperature continuously, and once the desired minimum is reached, it turns off the compressors and stops cooling; and once the maximum allowed is reached, it turns them on again.
  • The dynamics of teaching evaluation They serve to control how well the teaching dynamics works, since the class provides the teacher with the necessary information about the learning that takes place in it, and allows him to make adjustments in it.
  • A user satisfaction survey, provided by a company to its clientele so that they can return to the company the information they consider about the operation of the same.
  • Medical exams who draw our blood to see how healthy we are and with that information modify our diet or our lifestyle.

Examples of positive feedback:

  • How semiconductors work, whose ability to conduct electricity is greater the higher its temperature. When conducting a greater electrical charge, an increase in temperature is produced, which allows the charge to increase and so on, until the artifact is destroyed if no other process intervenes.
  • A fishing facility it extracts a certain quantity of food from the sea, with which it pays for its maintenance and obtains a surplus. If the latter is used to improve the facilities, it will be possible to fish more efficiently, increasing the money obtained and so on.
  • Sound feedbackAn unpleasant noise characteristic of misplaced microphones in a recording, it occurs when the audio signal emitted by the speakers is captured by the microphone and emitted again, amplifying the sound until it becomes noise.
  • How the capacity multipliers work, which are transistors configured to multiply the capacity of a capacitor, gaining current as it travels through the circuit. They are very common in electrical power supplies.


Positive and negative feedback homeostasis
Sweat is a negative feedback that favors homeostasis.

When the concept of feedback is applied to the human body and other living beings, it becomes evident that there are several processes designed to maintain the stability of the organism (that is, they are negative feedback processes), and others designed to increase its production of certain substances (positive feedback processes).

In both cases, the task is to allow the organism a vital adaptation to the environment. That is to say, positive and negative feedback in the body seek to maintain its homeostasis, its state of balance that guarantees a more or less prolonged existence.

Homeostasis it is an indispensable condition for life, which all living beings share, although through very different mechanisms. But from the tiniest microbe to large terrestrial mammals, everyone needs to regulate their bodily functioning through negative feedback and sometimes accelerate certain processes through positive feedback. For instance:

Homeostasis through negative feedback:

  • The body temperature of humans it must be kept in a very stable range so that its chemical processes take place unchanged. Therefore, there are temperature regulation mechanisms that are activated when it falls below what is acceptable (such as shivering, which generates muscle heat by repeatedly mobilizing the muscles, or the constriction of blood vessels to preserve the heat of the blood), or when it rises above what is acceptable (such as sweating to cool the skin, or vasodilation to allow the blood to cool).
  • When the oxygen demand of the body’s tissues increases, for example, when we perform physical exercise, the body responds increasing blood pressure so that the flow of oxygen is higher. When this demand decreases, the pressure also drops.
  • Faced with a drastic decrease in the calories available to the body (that is, when someone goes hungry), the body responds by trying decrease metabolic rate, that is, by slowing down energy consumption to delay the harmful effects of hunger. That is why people who try to lose weight through diets notice a slowdown in weight loss as the body compensates for the caloric decrease. The solution for this is to increase the need for calories, that is, to do physical exercise.

Homeostasis through positive feedback:

  • During the final moments of human pregnancy, the fully formed fetus has no space inside the womb and its head pushes the cervix. The maternal body, instead of counteracting this effect, responds by producing oxytocin, a hormone that stimulates uterine contractions so that the fetus can be expelled quickly. These contractions push the fetus forward, stimulating the production of more oxytocin, and so on until delivery. Otherwise the birth would be long and agonizing and would put the mother’s life at risk.
  • Something similar happens during intercourse, that is, sexual intercourse. The nerve endings stimulated during genital contact trigger the production of sex hormones that increase desire and feed back the process, increasing to lead in this way to orgasm and correct fertilization. It is a positive process whose purpose is to create new life.
  • Another example of this is accelerated digestion of certain proteins, which once they are detected in the digestive tract, trigger the production of digestive enzymes, allowing digestion to be a self-accelerating process: the more digestible proteins, the more enzymes are secreted. Otherwise, digestion could take much longer than it should.