In Pavlov's original experiment, what was the unconditioned stimulus (UCS)?
A: The bell
B: The sight of the laboratory
C: Food powder
D: The experimenter's footsteps
Correct: Food powder
Food powder was the unconditioned stimulus — it naturally and automatically triggered salivation (the unconditioned response) without any prior learning. The bell was the neutral stimulus that, after repeated pairing with food, became the conditioned stimulus, producing salivation on its own.
What is a conditioned response (CR)?
A: A response that occurs naturally to an unconditioned stimulus
B: A learned response triggered by a previously neutral stimulus
C: A response that has been extinguished through non-reinforcement
D: An innate reflex that cannot be modified by experience
Correct: A learned response triggered by a previously neutral stimulus
The conditioned response is a learned reaction elicited by the conditioned stimulus (CS) after it has been paired with the unconditioned stimulus. It is usually similar to, but weaker than, the unconditioned response. In Pavlov's experiment, salivation to the bell alone was the CR.
Extinction in classical conditioning occurs when:
A: The conditioned stimulus is repeatedly presented without the unconditioned stimulus
B: The unconditioned stimulus becomes too familiar to produce a response
C: A second conditioned stimulus is introduced
D: The organism is punished for the conditioned response
Correct: The conditioned stimulus is repeatedly presented without the unconditioned stimulus
Extinction occurs when the CS is presented repeatedly without being followed by the UCS. The conditioned response gradually weakens and disappears. Crucially, extinction does not erase the original learning — the association is suppressed rather than deleted, which is why spontaneous recovery can occur.
Spontaneous recovery refers to:
A: The return of a conditioned response after a rest period following extinction
B: The organism recovering its appetite after conditioning
C: The strengthening of a response after partial reinforcement
D: A new conditioned stimulus replacing an old one
Correct: The return of a conditioned response after a rest period following extinction
After extinction, if the organism is given a rest period and the CS is then presented again, the CR often reappears at reduced strength. This is spontaneous recovery. It demonstrates that extinction does not permanently erase the conditioned association — the original learning is still stored and can be reactivated.
Stimulus generalisation means that:
A: Only the exact original CS will trigger the CR
B: Stimuli similar to the CS also elicit the CR, to a lesser degree
C: The organism learns to distinguish between two similar stimuli
D: The UCS becomes less effective over time
Correct: Stimuli similar to the CS also elicit the CR, to a lesser degree
After conditioning, stimuli that resemble the original CS will also produce the CR, with the strength of the response decreasing as the new stimulus differs more from the original. This gradient of generalisation is adaptive — if a particular food made you ill, it makes sense to avoid similar-looking foods too.
In Watson and Raynor's "Little Albert" study (1920), a nine-month-old infant was conditioned to fear a white rat. What was the unconditioned stimulus?
A: The white rat
B: A loud, sudden noise
C: A flash of bright light
D: Being separated from his mother
Correct: A loud, sudden noise
Watson paired the white rat (neutral stimulus) with a loud clanging noise (unconditioned stimulus) that naturally produced distress and crying. After several pairings, Albert showed fear (CR) to the rat alone — and, through generalisation, to other white fluffy objects including a Santa Claus mask. The study demonstrated that phobias could be learned, not merely innate.
Systematic desensitisation, a therapy for phobias developed by Joseph Wolpe, is based on classical conditioning. Which principle underlies it?
A: Positive reinforcement for approaching the feared object
B: Graduated exposure paired with relaxation to extinguish the fear response
C: Flooding the patient with the feared stimulus until habituation occurs
D: Token rewards for completing fear-reduction tasks
Correct: Graduated exposure paired with relaxation to extinguish the fear response
Systematic desensitisation works through reciprocal inhibition: anxiety and relaxation cannot coexist. The patient constructs a hierarchy of fear-provoking situations and, while in a relaxed state, is progressively exposed to each — pairing the feared CS with relaxation rather than anxiety. This gradually extinguishes the conditioned fear response from mildest to most intense trigger.
Classical Conditioning
In Pavlov's original experiment, what was the unconditioned stimulus (UCS)?
About this quiz
Classical conditioning is one of the most fundamental forms of associative learning. First described by Ivan Pavlov through his work with dogs, it explains how a neutral stimulus can come to trigger a powerful response through repeated pairing with a stimulus that naturally produces that response.
This quiz covers the core concepts, terminology, and key experiments, including Pavlov's original work and Watson's controversial Little Albert study.