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.

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]

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.

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.

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]

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.
References in periodicals archive ?
The relative contributions of human settlers and a changing climate to ancient Australian animal extinctions remain controversial (SN: 6/18/05, p.
The creator of the term "biodiversity," he has warned of the dangers that plant and animal extinctions pose to the biosphere and its human inhabitants.
It should not be surprising that, on a global basis, 75 percent of all recent animal extinctions have occurred on islands.
Bailey's outrageous claims, such as that "there's a broad consensus that exposure to synthetic chemicals, even pesticides, does not seem to be a problem," "documented animal extinctions peaked in the 1930s," "global warming is not a serious problem," "increased wealth, population, and technological development [automatically?] preserve and enrich the environment," etc.
Some 75 percent of all known recent animal extinctions have been of island species.
In contrast, native species caused 2.7 percent of animal extinctions and 4.6 percent of plants.
Scientists say such changes are leading to drought, wildfires, rising sea levels, melting polar ice, plant and animal extinctions and other extreme conditions.
It shortened the timeframe in which humans are thought to have impacted on island ecosystems, particularly by way of deforestation and plant and animal extinctions, and that environmental transformations may have occurred over decades rather than centuries.
In explaining the process of animal extinctions, the book profiles scores of exotic and mundane creatures that have disappeared or in some cases come back from the brink of extinction.
So many magazines concerned with geography and the environment focus on how awful the state of the world is -- pollution, animal extinctions, humanity's abuse of the planet, and so on.