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 ?
Turnover was dominated by the loss of species rather than gain, and the highest species loss was detected between the river mouth and the lower river reach.
In response to this quandary, Sandler presents a positive account of how to deal with a loss of biodiversity in his fifth chapter: we need to develop relevant mitigation, adaption and compensation strategies that protect against species loss and support the instrumental and subjective final value of species and biodiversity but that are not too interventionist.
"The NAMPLACE project is designed to lift conservation barriers and advocates for the establishment of a large scale network of protected landscapes in order to address eminent threats to habitat and species loss at a landscape level, thereby ensuring greater responsiveness to variability and seasonality aspects that are inevitable due to climate change," says Environment Minister, Netumbo Nandi-Ndaitwah.
Researchers believe that the rate of species loss currently underway is 100-1,000 times faster than what was normal (the so-called "background rate" of extinction) prior to human overpopulation and its negative environmental effects.
The pace of species loss is also projected to gather pace as persistently hotter climate kicks in.n
We're making very little progress against species loss, deforestation, desertification and global warming.
To slow the rate of species loss, the new plan sets 20 targets organised under five strategic goals.
delegates plan to set a new target for 2020 for curbing species loss and discuss how to boost funding to assist poor countries in this task.
As the chief driving factor in species loss is habitat alteration, climate change is most definitely implicated in the great die-off, whether by heat, drought or flooding.
And then there's climate change and species loss. "It is time," Wells writes, "to take stock and realize that with great desires come great consequences."--Nathan Seppa Random House, 2010, 230 p., $26.
GEF projects have led to a marked slowing of species loss. The GEF is the world's largest supporter of protected areas.
He said species loss was 1,000 to 10,000 times higher than the natural extinction rate.