extinction

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extinction

 [eks-ting´shun]
in psychology, the disappearance of a conditioned response as a result of its not being reinforced; also, the process by which the disappearance is accomplished. See also conditioning.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ex·tinc·tion

(eks-tingk'shŭn),
1. In behavior modification or in classical or operant conditioning, a progressive decrease in the frequency of a response that is not positively reinforced; the withdrawal of reinforcers known to maintain an undesirable behavior.
2. Synonym(s): absorbance
[L. extinguo, to quench]
Farlex Partner Medical Dictionary © Farlex 2012

extinction

(ĭk-stĭngk′shən)
n.
1.
a. The act of extinguishing: The extinction of the fire took several hours.
b. The condition of being extinguished: mourned the extinction of her dreams.
2. The fact of being extinct or the process of becoming extinct: the extinction of the passenger pigeon; languages that are in danger of extinction.
3. Psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld.
4. Physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

extinction

Psychiatry A facet of operant–classical conditioning, in which the conditioned response is weakened and eventually disappears by nonreinforcement. See Operant conditioning, Respondent conditioning, Sensory extinction.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

ex·tinc·tion

(eks-tingk'shŭn)
1. In behavior modification or classical or operant conditioning, a progressive decrease in the frequency of a response that is not positively reinforced.
See: conditioning
2. Synonym(s): absorbance.
[L. extinguo, to quench]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

extinction

  1. the act of making EXTINCT or the state of being extinct.
  2. the elimination of an allele of a gene in a population, due to RANDOM GENETIC DRIFT or to adverse SELECTION pressures.
  3. any periodical, catastrophic event resulting in a species or larger taxonomic group dying out abruptly at a particular point in geological history. Such extinctions are thought to be cyclical, occurring every 28.4 million years, and have been attributed to cosmic activity such as showers of large asteroids or comets, though neither the periodicity nor its causes are at present universally accepted.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
"A key ingredient in this work, besides the environmental issues about species extinction, has been breaking down stereotypes and crossing barriers between cultures," he said.
Most conservation groups follow that approach: they try to protect biodiversity and limit species extinctions by creating wilderness reserves where human activity is limited or banned.
Over the past 200 to 300 years, humans have accelerated global species extinction rates 100-1,000 times Earth's historical geological background rate (Pimm et al., 1995; Mace, et al., 2005; Rockstrom et al., 2009), and modeled future extinction rates are projected to be 10,000 times the background rate (MEA, 2005).
2006), such indices may not only be used for estimating the probability of species extinction, but also to infer the threat and decline in species that are considered to be still extant.
There have always been periods of extinction in the planet's history but this rate of species extinction is higher than anything the world has experienced for the past 65 million years - the greatest rate of extinction since the vanishing of the dinosaurs.
There have always been periods of extinction in the planets history but this rate of species extinction is higher than anything the world has experienced for the past 65 million years - the greatest rate of extinction since the vanishing of the dinosaurs, he added.
'Places like these represent a healthy future for all of us and show that it is not too late to stop the current species extinction crisis,' says Dr Beehler, a Senior Research Scientist at Conservation International and expedition participant.
The poems in Regreen--about species extinction, the tar sands and the emotional loss and reverence of "the natural"--awaken new concerns, contemplations and questions about a planet in peril.
To help in our efforts, we can also point out the very significant contributions of meat consumption to disease, mistreatment of farmed animals, rapid species extinction, hunger, water scarcities, deforestation, desertification, soil erosion, and many more societal problems.
We all know about global warming, species extinction, and pollution, and we all know why these things are harmful to the earth.
The study warned that temperature rises of 2degC would still lead to wide scale damage such as species extinction and melting of ice sheets.
The human race overwhelms Earth's balancing and support systems with chemicals, air pollution, species extinction, and a dozen other activities that destroy this planet's ecosystems.