Editing Classical conditioning (section)

===Terminology===
In Pavlov's experiments the ''unconditioned stimulus (US)'' was the food because its effects did not depend on previous experience. The metronome's sound is originally a ''neutral stimulus (NS)'' because it does not elicit salivation in the dogs. After conditioning, the metronome's sound becomes the ''conditioned stimulus (CS)'' or conditional stimulus; because its effects depend on its association with food.<ref>{{cite book |first1=Douglas L. |last1=Medin |first2=Brian H. |last2=Ross |first3=Arthur B. |last3=Markmen |name-list-style=vanc |title=Cognitive Psychology |date=2009 |pages=50–53}}</ref> Likewise, the responses of the dog follow the same conditioned-versus-unconditioned arrangement. The ''conditioned response (CR)'' is the response to the conditioned stimulus, whereas the ''unconditioned response (UR)'' corresponds to the unconditioned stimulus.

Pavlov reported many basic facts about conditioning; for example, he found that learning occurred most rapidly when the interval between the CS and the appearance of the US was relatively short.<ref>{{cite book |vauthors=Brink TL |year=2008 |title=Psychology: A Student Friendly Approach |chapter-url=http://www.saylor.org/site/wp-content/uploads/2011/01/TLBrink_PSYCH06.pdf |chapter=Unit 6: Learning |pages=97–98 |access-date=2012-05-30 |archive-date=2012-04-16 |archive-url=https://web.archive.org/web/20120416041211/http://www.saylor.org/site/wp-content/uploads/2011/01/TLBrink_PSYCH06.pdf |url-status=live }}</ref>

As noted earlier, it is often thought that the conditioned response is a replica of the unconditioned response, but Pavlov noted that saliva produced by the CS differs in composition from that produced by the US. In fact, the CR may be any new response to the previously neutral CS that can be clearly linked to experience with the conditional relationship of CS and US.<ref name="Rescorla_1988"/><ref name="Bouton_2016"/> It was also thought that repeated pairings are necessary for conditioning to emerge, but many CRs can be learned with a single trial, especially in [[fear conditioning]] and [[conditioned taste aversion|taste aversion]] learning.

[[Image:delay,trace conditioning.svg|thumb|right|384px|Diagram representing forward conditioning. The time interval increases from left to right.]]