Classical Conditioning
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AP Psychology › Classical Conditioning
After one nausea episode from spoiled sushi, a person avoids sushi for months. What principle best explains this?
This is biological preparedness (taste aversion) because organisms readily learn food–illness associations, often after a single pairing.
This is spontaneous recovery because nausea returns after a rest period even though the person never eats sushi again.
This is generalization because the person avoids sushi only when it is served in the same restaurant as before.
This is fixed-ratio reinforcement because avoiding sushi is strengthened after being rewarded every set number of avoidance responses.
Explanation
Biological preparedness, specifically taste aversion learning, explains why a single pairing of sushi with nausea creates a lasting avoidance. Organisms are evolutionarily prepared to rapidly form associations between novel tastes and illness because this protects against poisoning. This specialized form of classical conditioning differs from typical conditioning by requiring only one trial, tolerating long delays between CS and UCS, and being highly resistant to extinction. This isn't generalization (which would involve avoiding similar foods), fixed-ratio reinforcement (an operant schedule), or spontaneous recovery (which involves return of an extinguished response). Taste aversion demonstrates how evolution shapes learning mechanisms for survival-relevant associations.
A dog stops salivating to a bell after many bell-only trials. Which phenomenon explains this decline?
Extinction, because presenting the CS repeatedly without the UCS weakens the CS–UCS association and reduces the CR.
Higher-order conditioning, because the bell becomes associated with a second neutral stimulus rather than with food.
Generalization, because the dog responds similarly to new sounds that resemble the bell heard during training.
Positive reinforcement, because salivating is followed by food and therefore increases salivating on later bell trials.
Explanation
Extinction occurs when the conditioned stimulus (bell) is repeatedly presented without the unconditioned stimulus (food), causing the conditioned response (salivation) to gradually weaken and disappear. The dog learns that the bell no longer predicts food, so the CS-CR association breaks down. This differs from generalization (responding to similar stimuli), positive reinforcement (an operant concept), and higher-order conditioning (pairing CS with new neutral stimulus). Extinction demonstrates that classical conditioning is reversible - learned associations can be unlearned when the predictive relationship between stimuli no longer holds.
A loud noise makes a baby startle. After a neutral rattle is paired with the noise, the rattle alone startles. What is the UCR?
Startling to the rattle, because it is the learned response elicited by the conditioned stimulus after conditioning.
Startling to the loud noise, because it is an unlearned reflexive response elicited by the unconditioned stimulus.
The rattle sound, because it begins as a neutral stimulus and later signals the loud noise after pairings.
Startling increases because the baby is reinforced with attention after startling, strengthening the behavior over time.
Explanation
The unconditioned response (UCR) is the natural, reflexive response that occurs to the unconditioned stimulus without any prior learning. In this example, the loud noise is the UCS that automatically triggers the startle response - this startling to the loud noise is the UCR. It's an innate defensive reflex that requires no conditioning. The rattle begins as a neutral stimulus and becomes the CS through pairing with the loud noise. The startling that occurs to the rattle alone after conditioning is the CR. This distinction between UCR (unlearned response to UCS) and CR (learned response to CS) is fundamental to understanding how classical conditioning creates new stimulus-response associations.
In Pavlov’s setup, food powder in a dog’s mouth automatically causes drooling. What is the drooling to food?
A punishment, because drooling reduces the likelihood of future food presentation in the experimental setting.
The UCR, because drooling is an unlearned reflexive response that occurs when the UCS (food) is presented.
The CR, because drooling occurs only after a bell becomes associated with food through repeated pairings.
The CS, because drooling starts as a neutral stimulus and later predicts the arrival of food powder.
Explanation
In classical conditioning, the unconditioned stimulus (UCS) naturally elicits an unconditioned response (UCR) without any learning. The conditioned stimulus (CS) becomes associated with the UCS through repeated pairings during acquisition. Food powder naturally causes drooling as an automatic reflex - this is the UCR to the UCS (food). The bell would be the CS that, after conditioning, elicits the CR (drooling). Extinction occurs when the CS is presented without the UCS, while spontaneous recovery is the return of the CR after a rest period. Stimulus generalization allows similar stimuli to elicit the CR, while discrimination restricts the response to specific stimuli.
A student hears the school bell (paired with stressful tests) and feels anxious. The anxiety is best labeled as what?
The UCR, because the bell naturally and automatically produces anxiety without any prior learning experiences.
The UCS, because anxiety is an unconditioned stimulus that causes the bell to occur in the school environment.
The CR, because anxiety is a learned response elicited by the CS after repeated pairings with stressful tests.
A reinforcer, because the anxiety increases bell-ringing behavior by providing a rewarding internal consequence.
Explanation
The conditioned response (CR) is the learned behavior that occurs when a conditioned stimulus (CS) is presented after acquisition. The school bell became a CS through repeated pairings with stressful tests (UCS), which naturally cause anxiety as an unconditioned response (UCR). After conditioning, hearing the bell alone elicits anxiety - this anxiety to the bell is the CR. The CR often resembles the UCR but is elicited by the learned CS rather than the natural UCS. Extinction could occur if the bell were heard repeatedly without stressful tests following. Spontaneous recovery might cause anxiety to return after extinction and a rest period. Generalization could cause anxiety to similar school sounds.
A tone is presented 10 seconds before an air puff; conditioning occurs faster than when tone follows the puff. What factor matters?
Overjustification, because external rewards reduce intrinsic motivation to blink when the tone is heard.
Generalization, because similar tones all become UCSs that naturally cause blinking without learning.
Fixed-ratio schedule, because reinforcement after a set number of blinks increases learning speed.
Timing/contiguity, because a CS that reliably precedes the UCS supports stronger prediction and faster acquisition.
Explanation
Timing and contiguity are crucial factors in classical conditioning effectiveness. For optimal acquisition, the conditioned stimulus (CS) should precede the unconditioned stimulus (UCS) by a short interval, typically 0.5-1 second. When the tone precedes the air puff by 10 seconds, it creates a reliable predictive relationship - the tone signals that the air puff is coming. This forward conditioning is more effective than simultaneous or backward conditioning because the CS serves as a predictor of the UCS. Poor timing reduces the CS's predictive value and weakens acquisition. The CS must reliably predict the UCS for strong conditioning to occur. This differs from operant conditioning where consequences follow behavior to modify future responses.
A light is paired with food until it elicits salivation; then a tone is paired with the light, and the tone elicits salivation. What is this?
Extinction, because presenting the tone without food gradually weakens salivation until it disappears.
Higher-order conditioning, because an established CS (light) conditions a new neutral stimulus (tone) to elicit the CR.
Operant chaining, because salivation is reinforced step-by-step through consequences following each response.
UCS substitution, because the light becomes a UCS that naturally produces salivation without learning.
Explanation
Higher-order conditioning occurs when an established conditioned stimulus (CS) is used to condition a new neutral stimulus, creating a chain of learned associations. First, the light became a CS through pairing with food (UCS), enabling it to elicit salivation as a conditioned response (CR). In the second phase, the tone (neutral stimulus) is paired with the light (now functioning as a conditioning stimulus), not with food directly. Through this process, the tone becomes a CS that can elicit salivation. This demonstrates that learning can occur through associations with other learned stimuli, not just primary reinforcers. The response is typically weaker than first-order conditioning and more susceptible to extinction.
A person feels fear when seeing a dog after being bitten; later, fear occurs to a dog leash alone. The leash is best described as what?
A primary reinforcer, because the leash directly satisfies biological needs and strengthens fear behavior as a consequence.
The UCR, because the leash is the automatic fear response produced by the dog bite without any learning.
The CS, because the leash becomes associated with the bite experience and later elicits a conditioned fear response.
The UCS, because the leash naturally causes fear without learning and requires no prior bite experience.
Explanation
A conditioned stimulus (CS) is initially neutral but gains the ability to elicit a conditioned response (CR) through repeated pairing with an unconditioned stimulus (UCS). Initially, the dog leash was neutral and produced no fear response. After the person was bitten by a dog (UCS), which naturally causes fear (UCR), the leash became associated with dogs and the bite experience. Through this association, the leash became a CS that can now elicit fear as a CR even when no dog is present. This demonstrates how classical conditioning can create phobias to objects associated with traumatic experiences. Extinction could occur through repeated exposure to the leash without negative consequences. Generalization might cause fear of other dog-related items.
After extinction, the conditioned response briefly returns the next day when the CS is presented. What is this called?
Spontaneous recovery, because an extinguished conditioned response reappears after a time delay without additional CS–UCS pairings.
Discrimination, because the organism learns to respond only to one specific CS and not to similar stimuli.
Avoidance learning, because the organism performs a behavior to prevent an aversive event from occurring again.
Acquisition, because repeated CS–UCS pairings gradually build the conditioned response from near zero to strong levels.
Explanation
Spontaneous recovery is the reappearance of an extinguished conditioned response after a rest period, without any new CS-UCS pairings. This phenomenon shows that extinction doesn't completely erase the learned association - it suppresses rather than eliminates it. The CR typically returns weaker than before extinction and will extinguish again quickly without renewed pairings. This differs from discrimination (differential responding), acquisition (initial learning), and avoidance learning (operant concept). Spontaneous recovery demonstrates that classical conditioning creates lasting memory traces that can resurface even after apparent extinction.
After tone–food pairings, the tone alone elicits salivation. What is the tone?
The conditioned response (CR), because it is the learned salivation that occurs after repeated pairings of tone and food.
A reinforcer, because salivation increases the likelihood the tone will be presented again in the future by the experimenter.
The conditioned stimulus (CS), because it was originally neutral and now triggers salivation after being paired with food.
The unconditioned stimulus (UCS), because it naturally produces salivation without any prior learning or pairing with another stimulus.
Explanation
In classical conditioning, a neutral stimulus (tone) becomes a conditioned stimulus (CS) through repeated pairings with an unconditioned stimulus (food). The tone initially has no effect on salivation, but after being paired with food (which naturally causes salivation), the tone alone can trigger salivation. This demonstrates acquisition, where the CS-UCS association is formed. The tone is not the UCS because it doesn't naturally cause salivation, nor is it the response itself (CR). Unlike operant conditioning where behaviors are reinforced, classical conditioning involves automatic responses to stimuli, so the tone isn't a reinforcer.