Psychology Chapter on Classical Conditioning

Initial Responses to the Stimuli

• Comparing responses elicited by stimuli before conditioning is crucial for identifying potential CSs and USs.
• The same stimulus can be a US in one experiment and a CS in another.

Novelty of Conditioned and Unconditioned Stimuli

• Learning occurs more slowly if either the CS or the US is familiar.
• Latent-Inhibition or CS-Preexposure Effect:
  • Repeated exposure to the CS without the US leads to habituation.
  • The CS becomes familiar and less significant, disrupting later pairing with the US.
  • This effect is called latent inhibition, suggesting it limits processing of inconsequential stimuli.
• US-Preexposure Effect:
  • Conditioning of the CS proceeds faster for an unfamiliar US compared to a familiar US.

CS and US Intensity and Salience

• The intensity of a stimulus influences its salience, which is its significance or noticeability.
• Salience can be increased by:
  • Making the stimulus more attention-grabbing.
  • Making it relevant to biological needs.
  • Making it similar to likely environmental encounters.

CS–US Relevance, or Belongingness

• Conditioning is influenced by the extent to which the CS is relevant to or "belongs" with the US.
• Garcia & Koelling (1966): Rats learn to associate:
  • Taste CS with illness US (natural).
  • Audio-visual CS with shock US (natural).
• CS-US relevance can be genetically determined, with faster learning of natural associations.
• Mineka and Öhman (2002): Fear conditioning is most effective in situations with recurring survival threats in mammalian evolution.

Learning Without an US

• Two forms of Classical Conditioning without a US:
  • Higher-order conditioning (HOC).
  • Sensory preconditioning.

A: Higher-Order Conditioning (HOC)

• Occurs in two phases:
  • First phase: Conditioning of a CS1 (e.g., lady) to a US (e.g., injury).
  • Second phase: Pairing a new CS2 (e.g., crowded theater) with the CS1 (now a conditioned stimulus), leading to a new CS2-US association without direct exposure to the US.
• HOC example: Fear of crowds leads to fear of theaters, which then becomes aversive without direct injury.
• Timing between CS1 and CS2 is crucial:
  • Simultaneous presentation: leads to conditioned inhibition.
  • Sequential presentation: leads to excitatory (HOC).

B: Sensory Preconditioning

• A two-phase process similar to HOC involving a previously established association between two neutral stimuli (e.g., vanilla and cinnamon).
• First phase: An association is formed between two neutral stimuli (CS1 and CS2).
• Second phase: One stimulus (CS1) is paired with the US, leading to aversion to both stimuli (CS1 and CS2).
• Example: If vanilla and cinnamon are associated, aversion learned towards cinnamon transfers to vanilla, even though vanilla was not directly paired with the US.

What Determines the Nature of the Conditioned Response?

• Several factors influence the type of conditioned response:
  • Nature of the US.
  • Nature of the CS.
  • CS-US interval.

1 - The US as a Determining Factor for the CR

• The nature of the US influences the CR, with the form of the CR resembling the form of the UR.
• Jenkins and Moore (1973): Different USs (food vs. water) elicit different CRs.
• Stimulus Substitution Model: Pavlov proposed that the CS activates neural circuits previously activated by the US, eliciting similar responses. This model is not fully accurate for all situations.

2 - The CS as a Determining Factor for the CR

• The nature of the CS can also influence the CR.
• Timberlake and Grant (1975): A CS (presence of another rat) paired with food elicited social affiliative responses instead of expected gnawing and biting behavior.

3 - The CS-US Interval as a Determining Factor for the CR

• The interval between the CS and the US influences the CR, leading to different behavioral responses based on the timing.
• Akins (2000): Short CS-US intervals (1 min) lead to sign tracking behavior, whereas longer intervals (20 min) encourage more locomotor behavior.

Behavior Systems Theory

• Explains how the CR is influenced by multiple factors (US, CS, interval), going beyond the stimulus substitution model.
• Presentation of a US activates the behavior systems relevant to that US.

Is it S-R vs S-S Learning?

• S-R learning: An association is learned between the stimulus and a response, directly elicited by the stimulus.
• S-S learning: An association is learned between two stimuli, with exposure to one activating a representation of the other.
• US Devaluation: Reduces the attractiveness of the US, leading to a decrease in the CR if the learning is S-S (the CS activates a representation of the US).

Blocking effect

• An existing association between CS1 and US prevents conditioning of a second CS (CS2) with the same US.
• Phase 1: Light (CS1) is paired with food (US).
• Phase 2: Light (CS1) is presented simultaneously with tone (CS2), followed by food (US).
• Test: Tone (CS2) is presented alone, showing weak or no conditioning effect if CS1-US association was previously established (blocking).

HOC vs. Blocking

• HOC: No US present during the second phase, only CS1 and CS2.
• Blocking: The US is present in both phases, but the existing CS1-US association prevents conditioning of CS2.

Surprise and US Effectiveness

• A surprising US (one that differs from expectations) is more effective in producing learning.
• Rescorla and Wagner: Developed a mathematical model of conditioning based on the concept of surprise.

Rescorla-Wagner Model

• A formal mathematical model that explains conditioning based on surprise.
• ΔV = k(λ – V):
  • ΔV: Change in value of association.
  • k: Constant.
  • λ: US.
  • V: Value of the US.
  • Surprise factor: (λ – V)
• First trials: US is surprising (λ > V).
• As trials increase, the US becomes less surprising (λ = V).
• Increased surprise to unexpected US enhances conditioning.

Explore the key concepts of classical conditioning, including the roles of conditioned and unconditioned stimuli. Understand how familiarity and intensity influence learning, as well as the effects of latent inhibition and preexposure. Test your knowledge on the dynamics of stimulus response and attention in conditioning.