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

/ex·tinc·tion/ (eks-tink´shun) in psychology, the disappearance of a conditioned response as a result of nonreinforcement; also, the process by which the disappearance is accomplished.

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

[iksting′shən]
a state of being lost or destroyed.

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.

extinction

the disappearance of a conditioned response as a result of nonreinforcement.
References in periodicals archive ?
In lieu of any direct way to measure the rate of species loss, conservationists have relied on reversing the so-called "species-area relationship," whereby scientists tally the number of species in a given area and then estimate how quickly more show up or evolve as viable habitat increases (or decreases in the case of reversing the concept).
Students also learn the cascading consequences of species loss.
6) A highly influential study by economists William Nordhaus and Joseph Boyer treats the welfare cost of species loss as too small or uncertain to be accurately quantified.
Efforts to save the baiji, which is reportedly the first cetacean species loss due to human involvement, were hampered by Chinese and Western disputes about the best way to preserve the species, according to The baiji.
There is growing concern that this species loss will have important effects on ecosystem functioning: that species-poor ecosystems may perform differently, or less efficiently than the species-rich systems from which they are derived (Zedler et al.
Problems like climate change, species loss, and habitat destruction can also seem overwhelmingly large, so another challenge is to focus on the solutions and convince people that their own actions, no matter how small, make a difference.
The alliance's statement calls for "human dominion over creation" and insists that global warming, over-population and large-scale species loss are "unfounded or undue concerns.
This development comes at the price of species loss, not only of the trees themselves but of the life they support.
Species loss may also mean the loss of valuable models for medical research, said Chivian.
It seems it's far easier, however, to target a small duck than the real cause of species loss.
The tragedy, say many green leaders, is that Americans are tuning out the environment at the very time that big-ticket crises--from global warming to endangered species loss and overfishing of the oceans--need immediate attention.
The book opens with masterly and engaging accounts of deforestation, species loss, agricultural expansion, and the establishment of irrigation.