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A simple negative feedback system is descriptive, for example, of some electronic amplifiers. The feedback is negative if the loop gain AB is negative.. Negative feedback (or balancing feedback) occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by ...
Perceptual control theory (PCT) is a model of behavior based on the properties of negative feedback control loops. A control loop maintains a sensed variable at or near a reference value by means of the effects of its outputs upon that variable, as mediated by physical properties of the environment.
Psychologist Jonathan Freedman's experiment recruited high school and university students to carry out a series of experiments that measured the effects of density on human behavior. He measured their stress, discomfort, aggression, competitiveness, and general unpleasantness. He declared to have found no appreciable negative effects in 1975. [15]
An experiment conducted by Solomon and Wynne [7] in 1953 shows the properties of negative reinforcement. The subjects, dogs, were put in a shuttle box (a chamber containing two rectangular compartments divided by a barrier a few inches high). The dogs had the ability to move freely between compartments by going over the barrier.
This is an example of a locally acting (negative feedback) mechanism. An example of upregulation is the response of liver cells exposed to such xenobiotic molecules as dioxin . In this situation, the cells increase their production of cytochrome P450 enzymes , which in turn increases degradation of these dioxin molecules.
Negative feedback: If the signal feedback is out of phase by 180° with respect to the input signal, the feedback is called negative feedback. As an example of negative feedback, the diagram might represent a cruise control system in a car that matches a target speed such as the speed limit. The controlled system is the car; its input includes ...
Fundamental to Lorenz's theory of ecology is the function of negative feedback mechanisms, which, in hierarchical fashion, dampen impulses that occur beneath a certain threshold. The thresholds themselves are the product of the interaction of contrasting mechanisms.
Negative feedback processes are those that maintain particular conditions by reducing (hence 'negative') the difference from a desired state, such as where a thermostat turns on a heater when it is too cold and turns a heater off when it is too hot. Positive feedback processes increase (hence 'positive') the difference from a desired state. An ...