(1) A feedback in which the system responds to the perturbation in the same direction as the perturbation.
In this system, the original perturbation signal is amplified, and the output can grow exponentially or even hyperbolically.
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.