Extinction: The weakening of a reinforced operant response as a result of ceasing reinforcement. See also operant conditioning. Also, the elimination of a conditioned response by repeated presentations of a conditioned stimulus without the unconditioned stimulus. See also respondent conditioning.

 

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Extinction: The elimination of all individuals in a group, both by natural (dinosaurs, trilobites) and human-induced (dodo, passenger pigeon, liberals [:)]) means.

Ordovician Extinction: Paleozoic-aged mass extinction possibly related to glaciation in the southern-hemisphere supercontinent Gondwana.

Secondary Extinction: The death of one population due to the extinction of another, often a food species.

Mass Extinction: A time during which extinction rates are generally accelerated so that more than 50% of all species then living become extinct; results in a marked decrease in the diversity of organisms. Ma . . . View Full Definition

Sensory Extinction: Failure to report sensory stimuli from one region if another region is stimulated simultaneously, even though when the region in question is stimulated by itself, the stimulus is correctly reported.

Extinction Angle: The angle between a crystallographic direction, such as a face or cleavage plane, and the direction in which all light is blocked by a pair of crossed polarizers.

Extinction Meter: Early type of exposure calculator.

Absorptivity: (a) extinction coefficient; absorption cross section; decadic absorptivity. Compare with molar absorptivity and absorbance. The absorbance of a solution per unit of path length and per unit . . . View Full Definition

Absorbance: (A, D, E) optical density; extinction; decadic absorbance. A measure of the amount of light absorbed by a sample. The absorbance (A) equals minus the base-10 log of the transmittance.

Colonialism: The term refers broadly and generally to the habit of powerful civilizations to 'colonize' less powerful ones. On the obvious level, this process can take the form of a literal geographic oc . . . View Full Definition