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341770_ch_05.qxd 6/4/02 12:29 PM Page 185 mac 106 mac 106:211_sks: MODU LE 5.1 185 CONCEPT CHART 5.1 Key Concepts in Classical Conditioning Concept Description Example: Fear of Dentistry Classical conditioning A form of learning in which a response identical or similar to one originally elicited by an unconditioned stimulus (US) is made in response to a conditioned stimulus (CS) based on the pairing of the two stimuli The pairing of pain during dental procedures with environmental stimuli in the dentist’s office leads to the development of a fear response to the environmental cues alone. Extinction Gradual weakening and eventual disappearance of the conditioned response (CR) when the CS is repeatedly presented without the US The use of anesthetics and painless dental techniques leads to the gradual reduction and elimination of fear of dentistry. Spontaneous recovery Spontaneous return of the CR some time after extinction occurs Fear of dentistry returns spontaneously a few months or a few years after extinction. Stimulus generalization CR evoked by stimuli that are similar to the original CS Person shows a fear response when visiting the office of a new dentist. Stimulus discrimination CR not evoked by stimuli that are related but not identical to the CS Person shows a fear response to the sight of a dentist’s drill but not to equipment used for cleaning teeth. Higher-order conditioning CR evoked by a new stimulus that is paired with a CS that already elicits the response Person cringes upon hearing the dentist’s name. higher-order conditioning The process by which a previously neutral stimulus comes to elicit a conditioned response as a result of its being paired with a conditioned stimulus that already elicits the conditioned response. (US) that were preceded by a tone (CS) either on all occasions or on most, but not all, occasions. The rats whose shocks were always preceded by the tone learned a conditioned response of fear to the tone alone, whereas the rats whose shocks were usually, but not always, preceded by the tone did not. Rescorla argued that classical conditioning depends on more than the simple pairing of stimuli; it requires that the CS come to reliably predict the occurrence of the US. Rescorla’s perspective on classical conditioning is a cognitive one. In his view, humans and other animals actively seek information that helps them make predictions about important events in their environment. Conditioned stimuli are cues that organisms use to make these predictions. Rescorla’s model, which has been supported by other research (R. R. Miller, Barnet, & Grahame, 1995), has important survival implications. Dogs and other animals may be more likely to survive if they learn to respond with salivation to cues that food is present, since salivation helps them prepare to swallow food. Animals are also more likely to survive if they learn a fear response (heightened bodily arousal) to cues that signal the presence of threatening stimuli. Bodily arousal helps the animal prepare either to fight off a potential threat, or to flee from it. Consider an animal that hears a sound or gets a whiff of an odor (a CS) previously associated with the presence of a particular predator (a US). By responding quickly with heightened arousal to such a stimulus, the animal is better prepared to take defensive action if the predator appears. Thus, classical conditioning serves as a kind of built-in early warning system. Rescorla’s model also explains why you are likely to develop a fear of dentistry more quickly if you experience pain during each dental visit than if you have pain only every now and then. In other words, the more reliably the CS (dental cues) signals the occurrence of the US (pain), the stronger the conditioned response is likely to be.