Overview: Feedback loops are cause-and-effect processes within organisms and systems. Negative feedback loops serve to maintain homeostasis or equilibrium. Positive feedback loops are used to intensify or change the status of a system.
Originators: Karl Ferdinand Braun (1850-1918), Henri Louis Le Chatelier (1850-1936)
Keywords: homeostasis, feedback, cause-and-effect system, circuit, circle, positive feedback, negative feedback, closed system, amplify
The concept of feedback loops has been around since the 18th century, but the actual term “feedback” wasn’t used until later. In the 1880s, Karl Ferdinand Braun and Henri Louis Le Chatelier separately discovered how systems tend to respond to stimuli by seeking to establish a new equilibrium.[i] The concepts behind their research form the basis of current information on feedback loops.
Feedback loops allow organisms and systems to maintain control of important processes by signaling back whether an input should be intensified or stopped. In its simplest form, a feedback loop might include two factors, which can be labeled A and B. In the feedback loop, A impacts B, and this stimulation of B leads it to have a return impact on A.
Feedback loops are often much more complex than this, and can include more than two factors. Feedback loops can be either positive or negative, with each type of feedback loop being used in different types of processes.
Negative Feedback Loops
A negative feedback loop seeks to maintain homeostasis. Homeostasis is the ability to stay within specific boundaries so that an organism or system can function at optimal levels.
A furnace thermostat is an example of a negative feedback loop. This negative feedback system allows a house to stay at a proper temperature, without becoming too hot or too cold. Based on the set temperature, a thermostat signals to a furnace that more heat is needed. The furnace produces more heat, and once the heat reaches the set temperature, the heat signals the thermostat to turn the furnace off. Should the temperature in the room decrease, the thermostat is trigged once more to turn the furnace back on, and the feedback loop continues. In this way, the thermostat triggers the furnace to turn on and off throughout the day to maintain the proper temperature.
Positive Feedback Loops
Positive feedback loops don’t seek to maintain homeostasis; rather, they move organisms or systems away from homeostasis, seeking to intensify or change certain processes.[ii]
Childbirth is an example of a positive feedback loop. In the case of childbirth, the body must move steadily away from homeostasis for the baby to be safely born. Hormones and nerve impulses in the body lead to contractions, which cause the baby to be pushed against the cervix. This pressure against the cervix signals more nerve impulses which intensifies contractions and continues the loop around again. Rather than keeping the body within a set of boundaries, the goal of this positive feedback loop is to amplify contractions more and more until the child is born.
Using Feedback Loops to Improve Organizations
Feedback loops are natural mechanisms found in a variety of fields such as biology, physics, engineering, and mathematics. People have observed these feedback loops in nature and considered how this concept can help organizations and groups of people function more effectively.
Many academic institutions, places of employment, and businesses ask their students, employees, and customers to fill out feedback forms. Feedback forms typically ask for suggestions for how the organization can improve. A common problem is that these institutions fail to close the feedback loop by taking action based on the results of the feedback. For the system to function as an actual loop, the organization needs to respond and put into practice the suggestions that were made.[iii]
References
[i] Norwich, K H. (2010). Le Chatelier’s principle in sensation and perception: Fractal-like enfolding at different scales. Frontiers in Physiology, 1(17).
[ii] OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 26, 2016 http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.24.
[iii] Watson, S. (2003) Closing the feedback loop: Ensuring effective action from student feedback. Tertiary Education and Management, 9, 145-157.
