notes classical conditioning

🧠 Classical Conditioning – AP Psychology Notes

1. What Is Classical Conditioning?

Classical conditioning is a type of learning where an organism learns to associate two stimuli, so that one stimulus comes to elicit a response originally produced by another stimulus.

• Discovered by Ivan Pavlov
• Involves reflexive, automatic responses (not voluntary behavior)

📌 Key idea: learning happens before behavior

2. Basic Components

Unconditioned Stimulus (UCS)
→ A stimulus that naturally and automatically triggers a response
Example: Food

Unconditioned Response (UCR)
→ An unlearned, automatic response to the UCS
Example: Salivation to food

Neutral Stimulus (NS)
→ A stimulus that does not initially cause a response
Example: Bell (before learning)

Conditioned Stimulus (CS)
→ A previously neutral stimulus that, after pairing, triggers a response
Example: Bell (after learning)

Conditioned Response (CR)
→ A learned response to the CS
Example: Salivation to bell

3. Acquisition

Acquisition is the initial learning phase where the NS is paired repeatedly with the UCS.

• Strength of CR increases with repeated pairings
• Conditioning is complete when CS alone produces the CR

📌 Best learning occurs when CS predicts UCS

4. Timing and Conditioning Schedules

Simultaneous Conditioning
CS and UCS occur at the same time
→ Weak learning

Delayed Conditioning (BEST)
CS occurs before UCS and overlaps
→ Strongest conditioning

Trace Conditioning
CS ends before UCS begins
→ Moderate learning (memory required)

Backward Conditioning
UCS occurs before CS
→ Poor or no learning

Temporal Conditioning
Time itself acts as the CS
Example: Dog salivates at 5:30 PM when usually fed

5. Salience

Salience = how noticeable or meaningful a stimulus is

• More biologically relevant stimuli = faster learning
• Fear + scream = strong association
• Bell + food = weaker, takes longer

6. Contiguity vs Contingency

Contiguity (Pavlov)
Learning depends on timing
Stimuli occur close together in time

Contingency (Rescorla)
Learning depends on predictability
CS must reliably predict UCS

📌 Modern psychology supports contingency more than contiguity

7. Extinction occurs when a conditioned response decreases or disappears after repeated presentations of the conditioned stimulus without the unconditioned stimulus. This process illustrates the importance of the association between the two stimuli and highlights the dynamic nature of learning.

Extinction occurs when the CS is repeatedly presented without the UCS

• CR weakens and disappears
• Not unlearning, but suppression

Example: Bell rings, no food → salivation fades

8. Spontaneous Recovery

The reappearance of a previously extinguished CR after a rest period

• No new pairing required
• Shows learning was not erased

9. Generalization

CR occurs to stimuli similar to the CS

• More similarity = stronger CR
Example: Dog salivates to doorbell, phone ring, alarm

10. Discrimination

Ability to distinguish between stimuli

• Respond only to the specific CS
• Learned through extinction of similar stimuli

11. Second-Order Conditioning

A CS becomes associated with a new neutral stimulus

CS₁ → CR
CS₂ + CS₁ → CR
CS₂ → CR

Example:
Bell → salivation
Light + bell → salivation
Light → salivation

📌 Second-order responses are weaker

12. Blocking

Prior learning prevents new learning

If CS₁ already predicts UCS, adding CS₂ won’t be learned

Example:
Bell → food
Bell + light → food
Light alone → no response

13. Biological Constraints on Conditioning

Equipotentiality (Old View)
Any stimulus can be paired with any response

❌ Not always true

14. Taste Aversion (Garcia & Koelling)

Animals easily associate taste with nausea, even with long delays

• Violates Pavlov’s timing rule
• Learned in one trial
• Extremely resistant to extinction

15. Biological Preparedness

Organisms are biologically predisposed to form certain associations

• Taste → illness
• Sound/light → shock
• Adaptive for survival