Psychology of Learning

Module 04: Classical Conditioning 1

Summary

Basics of Classical Conditioning

Ivan Pavlov discovered that neutral stimuli could acquire the power to elicit responses when paired with unconditioned stimuli (US). Key terms:

• US: stimulus that reflexively elicits a response (e.g., food).
• UR: innate response to the US (e.g., salivation).
• CS: previously neutral stimulus that gains power through pairing (e.g., metronome).
• CR: learned response to the CS (e.g., salivation to metronome). Classical conditioning occurs in everyday life, such as taste aversions, shower scalding, or emotional associations. Clinical applications include exposure therapy for phobias.

Acquisition & Extinction

• Acquisition: CR develops through repeated CS–US pairings. Stronger USs & optimal timing (CS preceding US, ~0.5s interval) enhance learning. Exceptions include taste aversion, which can occur after a single pairing.
• Extinction: presenting CS without US reduces CR strength. Extinction reflects new learning that the CS no longer predicts the US.
• Spontaneous recovery: extinguished CRs can reappear after time, showing original learning persists.
• Resistance to extinction: stronger conditioning produces more persistent CRs.
• Conditioning differs with appetitive USs (food, pleasure) versus aversive USs (shock, nausea). Pavlov’s “experimental neurosis” showed how impossible discrimination tasks can cause distress.

Generalization & Discrimination

• Generalization: stimuli similar to the CS elicit CRs, producing a gradient of responding. Adaptive for survival (e.g., responding to similar predator sounds).
• Discrimination: organisms learn to respond selectively to CS+ (paired with US) & not to CS– (unpaired). Training narrows the generalization gradient.
• Clinical research shows fear overgeneralization contributes to anxiety disorders.
• Higher‑order conditioning: a CS can act as a US for new learning, though responses weaken with each step.
• Sensory preconditioning: two neutral stimuli paired together can later transfer conditioning.
• Sign tracking (autoshaping): organisms investigate CSs predicting USs, treating them as significant.
• Conditioned emotional responses (CERs): CSs paired with aversive USs elicit fear that suppresses ongoing behavior.
• Conditioned inhibition: CS– signals US omission, actively reducing responding. Measured through retardation & summation tests.
• Contingency: conditioning depends on predictive relationships—positive (CS signals US), zero (no prediction), or negative (CS signals US absence).

Conclusion

Module 04 demonstrates classical conditioning as the first true learning process, showing how organisms form predictive associations. From Pavlov’s foundational work to modern applications, conditioning explains everyday behaviors, emotional responses, & clinical treatments. It highlights both the flexibility & limits of associative learning.