Positive feedback

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(1) A feedback in which the system responds to the perturbation in the same direction as the perturbation.

(2) A feedback mechanism resulting in the amplification or growth of the output signal.


In this system, the original perturbation signal is amplified, and the output can grow exponentially or even hyperbolically.

A positive feedback is a closed system as it occurs in a feedback loop. It means the response of the system relies on the feedback signal to function.

One example of biological positive feedback is at the onset of contractions in childbirth. When contraction occurs, oxytocin is released into the body stimulating more contractions. Thus, the result is an increased amplitude and frequency of contractions.

Compare: negative feedback.
See also: feedback mechanism.