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The dominant account of extinction involves associative models. However, there is debate over whether extinction involves simply "unlearning" the unconditional stimulus (US) – Conditional stimulus (CS) association (e.g., the Rescorla–Wagner account) or, alternatively, a "new learning" of an inhibitory association that masks the original excitatory association (e.g., Konorski, Pearce and ...
Extinctions are a normal part of the evolutionary process, and the background extinction rate is a measurement of "how often" they naturally occur.Normal extinction rates are often used as a comparison to present day extinction rates, to illustrate the higher frequency of extinction today than in all periods of non-extinction events before it.
Limited geographic range is the most important determinant of genus extinction at background rates but becomes increasingly irrelevant as mass extinction arises. [45] Limited geographic range is a cause both of small population size and of greater vulnerability to local environmental catastrophes.
Permian–Triassic extinction event 252 Ma Large igneous province (LIP) eruptions [ 23 ] from the Siberian Traps , [ 24 ] an impact event (the Wilkes Land Crater ), [ 25 ] an Anoxic event , [ 26 ] an Ice age , [ 27 ] or other possible causes
Extinction is not only when a previously learned value lessens, but also when a new association being created leads to a new value being learned. [15] However, this cannot be used to explain why desensitization works, as it solely describes the functional relationship between absent reinforcement and phobic responses and lacks an actual ...
Extinction is the absence of a rewarding stimulus, which weakens behavior. Writing in 1981, Skinner pointed out that Darwinian natural selection is, like reinforced behavior, "selection by consequences".
Now, however, background performers could truly disappear. Already threatened by the advancement in special effects that create computer-generate crowds, the background acting community is bracing ...
Human extinction or omnicide is the hypothetical end of the human species, either by population decline due to extraneous natural causes, such as an asteroid impact or large-scale volcanism, or via anthropogenic destruction (self-extinction).