Psychology of Learning

Module 05: Classical Conditioning 2

Summary

Challenges to Traditional Views

Taste aversion learning revealed biological constraints on conditioning. Unlike typical conditioning, taste aversions can occur after a single pairing, tolerate long CS–US intervals (up to 24 hours), & are highly resistant to extinction. Garcia & Koelling’s (1966) experiments showed preparedness: rats associate internal cues (taste) with illness & external cues (light/sound) with shock. Species differences (rats vs. quail) highlight evolutionary adaptations. These findings overturned the assumption of equipotentiality, showing that not all CS–US combinations are equally learnable.

Cue Competition & Extinction Effects

• Blocking: prior conditioning of one CS prevents conditioning of another if the US is already predicted.
• Overshadowing: in compound CSs, the more salient stimulus dominates learning.
• Potentiation: in taste aversion, pairing odor with taste enhances odor conditioning.
• Drug tolerance: contextual cues act as CSs eliciting compensatory CRs opposite to URs, explaining tolerance & overdose risks.
• Extinction: not erasure but new inhibitory learning. Evidence includes facilitated reacquisition (faster relearning) & renewal (return of CR in original context). These show extinction is context‑dependent.

Theoretical Accounts

• Pavlov’s stimulus substitution theory: CS activates US brain centers (S–S associations). Later evidence supported S–S over S–R links.
• Rescorla‑Wagner model: learning depends on prediction error (surprise). Explains acquisition, blocking, extinction, overshadowing, & predicts phenomena like the overexpectation effect.
• Comparator hypothesis: CR strength depends on relative predictiveness of CS compared to context. Explains effects of trial spacing & context dependency.

Physiological Mechanisms

Research in Aplysia showed conditioning increases neurotransmitter release at synapses, while mammalian studies revealed distributed brain systems: cerebellum (eyeblink), amygdala (fear), hippocampus (context), insular cortex (taste aversion). Conditioning involves distinct circuits for different CRs.

Applications to Phobias & Treatment

Classical conditioning explains phobia development (e.g., claustrophobia from traumatic confinement). Treatments include:

• Flooding: intense exposure until fear subsides.
• Systematic desensitization: gradual exposure paired with relaxation.
• Addressing renewal requires extinction across multiple contexts to prevent relapse.

Conclusion

Module 05 demonstrates that classical conditioning is not a uniform process but shaped by biological preparedness, cue competition, prediction error, & context effects. These insights deepen our understanding of associative learning & inform practical applications from wildlife management to phobia treatment.