Pavlovian Conditioning – Study Notes

Core Concepts of Pavlovian Conditioning

  • Learning is the enduring change in an organism’s response based on experience; learning is about predicting the future and guiding behaviour.
  • Three core assumptions shared by many learning theories:
    • Experience shapes behaviour
    • Learning is adaptive
    • Well-designed experiments can uncover the laws of learning
  • Pavlovian conditioning (classical conditioning) involves learning that one stimulus predicts another; it is distinct from operant conditioning (learning that a behaviour leads to an outcome) and observational learning (learning by watching others). These three types can co-occur in real life.

Acquisition and Basic Processes

  • Acquisition is the initial stage of learning where the neutral stimulus (NS) is repeatedly paired with the unconditioned stimulus (US), which naturally elicits the unconditioned response (UR).
    • Formal representation during acquisition: NS+US→UR\text{NS} + \text{US} \rightarrow \text{UR}
  • After repeated pairings, the NS becomes the conditioned stimulus (CS) and elicits a conditioned response (CR), which is often similar to the UR but may differ in strength or form.
    • Formal representation after conditioning: CS→CR\text{CS} \rightarrow \text{CR}
  • Example from Pavlov’s work: dogs salivate to food (US) producing UR; a bell (NS) becomes a CS after conditioning and salivation to the bell (CR) occurs.

Unconditioned Stimulus and Unconditioned Response

  • Unconditioned Stimulus (US): a stimulus that naturally elicits a response without prior learning.
  • Unconditioned Response (UR): the automatic, reflexive response to the US.
  • In a typical Pavlovian sequence: US elicits UR automatically; no learning is required for this response.

Neutral Stimulus and Conditioned Stimulus

  • Neutral Stimulus (NS): a stimulus that initially does not elicit a response; becomes the Conditioned Stimulus (CS) after pairing with the US.
  • Conditioned Stimulus (CS): the formerly neutral stimulus that now elicits a conditioned response (CR) after conditioning.

The Learning Curve and Acquisition Evidence

  • The acquisition curve shows increasing CR strength across acquisition trials as the CS begins to predict the US.
  • The learning curve can be plotted by measuring the CR (for example, salivation) across successive acquisition trials.

Factors That Determine Acquisition/Learning

  • Factors influencing acquisition:
    • 1) CS should be novel, salient, and intense.
    • 2) US should be contingent on the CS (the US should not occur without the CS).
    • 3) Contiguity: US and CS must occur in the same place at the same time.
  • Primary function: Pavlovian conditioning helps the organism predict important biologically relevant events.

Classic Experiments: Pavlov and Little Albert

  • Pavlov’s dogs: salivation to food (US) and the use of a bell as NS that becomes CS after conditioning.
  • Little Albert (Watson & Rayner, 1920): an infant initially showed no fear; CS was a white rat paired with a loud US to evoke fear (UR). After conditioning, the rat became a CS that elicited a fear response (CR).
  • Generalisation: fear response extended from the white rat to other similar white, fluffy objects (e.g., white rabbit, dog, fur coat) but not to dissimilar objects (e.g., building blocks).

Generalisation

  • Fear generalisation occurs when learned fear extends to similar cues or situations.
  • In Little Albert, fear generalized to other white, fluffy items but not to dissimilar items; prior to conditioning, these items elicited neutral responses.

Extinction

  • Extinction is an active process: presenting the CS without the US repeatedly reduces the CR.
  • It is not simply forgetting with the passage of time; forgetting is time-dependent, while extinction results from new CS-alone experiences.
  • After extinction, presenting the CS alone repeatedly leads to a reduction in the CR; the original CS–US association remains but is suppressed.

Extinction Curves and Data

  • Extinction trials show a decline in the CR (e.g., salivation) when the CS is presented without the US over time, reflecting extinction learning.

Relapse Phenomena

  • Relapse phenomena show that the CS–US association is not forgotten during extinction; the CR can reappear under certain conditions.
  • Three main relapse phenomena:
    • Spontaneous recovery: CR returns after a delay following extinction.
    • Reinstatement: CR returns after exposure to the US alone, following extinction.
    • Renewal: CR returns when the context changes after extinction.

Spontaneous Recovery

  • The return of the CR after extinction indicates that the original association is still present and the extinction learning may fade with time.
  • Example pattern: after extinction, a delay followed by a test shows a partial return of salivation to the CS.

Renewal

  • Renewal occurs when extinction learning is context-bound and the original learning is more generalized; changing context from the extinction context to a different context can trigger the CR again.
  • Conceptual illustration: Context A (home) vs Context B (vet’s office); CS present in both but CR reappears when the context changes.

Reinstatement

  • Reinstatement occurs when re-exposure to the US after extinction causes the CS–CR association to re-emerge.
  • Mechanism: the US reintroduces the possibility of learning the CS again, lifting the suppression that occurred during extinction.

How to Treat Little Albert?

  • Historical note: the ethical and methodological limits prevented further extinction-based intervention with Little Albert in the original setting.
  • Modern takeaway: extinction is a viable method for reducing conditioned emotional responses (with proper ethics and contemporary therapeutic contexts).

Exposure Therapy for Arachnophobia and Specific Phobias

  • Exposure therapy is the gold standard treatment for specific phobias.
    • Supported by meta-analyses across multiple sources: Kuleli et al. 2025; Wolitzky-Taylor et al. 2008; Weschler et al. 2019.
  • In vivo exposure (real-life exposure) tends to be more effective than imaginal exposure; virtual reality findings are mixed.

Specific Phobias and Conditioning

  • Are phobias acquired through conditioning?
    • Sometimes, but not always.
  • Phobias can arise from multiple pathways:
    • Traumatic experiences (eg, a fall leading to fear of heights)
    • Modelling or observational learning (seeing a caregiver act scared around a stimulus)
    • Transmission of misinformation or myths about danger (eg, unsafe claims about peanuts)
    • Evolutionary preparedness predispositions can bias certain fears more readily than others

Evolutionary Preparedness and Specific Phobias

  • Evolutionary preparedness: organisms are biologically predisposed to form certain CS–US associations more easily because they are adaptive for survival and reproduction.
  • Why spiders and snakes are more commonly feared than cars:
    • Deaths related to road accidents are high compared to snake or spider bites, but fear is often biased toward stimuli historically associated with danger.
    • There is no strong selective pressure to fear cars; however, fear of heights is an example of preparedness that can reduce phobias rather than increase them.
  • Mechanism: in preparedness, the organism is predisposed to learn fear toward certain stimuli more readily; even negative experiences with prepared stimuli can sometimes reduce fear in those contexts.

Garcia & Koelling Preparedness Experiments (1966)

  • Design: Rats exposed to a compound CS consisting of light + sound + flavored water (CS1, CS2, CS3). Two groups received different USs:
    • Group 1: US = foot shock (pain) accompanying each lick of water
    • Group 2: US = radiation-induced nausea (x-rays)
  • Test: avoid each CS individually to see which CS elicits avoidance after conditioning.
    • Group 1 (foot shock): avoided light CS and sound CS, but not flavored water CS
    • Group 2 (nausea): avoided flavored water CS, but not light CS or sound CS
  • Conclusion: Preparedness matters; organisms learn to avoid cues that are biologically relevant to the given US; not all CSs are equally tied to every US.

Taste Aversion and One-Trial Learning

  • Taste aversion demonstrated that one strong CS–US pairing can produce a robust CR even with a long delay between CS and US.
  • This finding posed a challenge to some traditional accounts of Pavlovian conditioning, which assumed shorter CS–US intervals were necessary for learning.

Preparedness (General) and Its Role in Conditioning

  • Preparedness helps explain why some fears are more common and more easily learned than others.
  • It also explains why certain negative experiences with evolutionarily prepared stimuli do not always translate into stronger phobias and may even reduce fear in those contexts.

Pavlovian Conditioning Summary

  • Pavlovian conditioning involves learning the association between two events: a CS and a US, leading to a CR.
  • After conditioning, repeated CS-alone presentations produce extinction; the CR diminishes but the original CS–US association can re-emerge under relapse phenomena.
  • Extinction is foundational for exposure therapies in treating specific phobias and other anxiety disorders.
  • Phobias can arise from Pavlovian conditioning but also from trauma, modelling, misinformation, and evolutionary predispositions.
  • Avoidance of the conditioned stimulus prevents extinction from occurring, perpetuating phobias.
  • Evolutionary and biological preparedness helps explain why some associations are more readily learned than others, shaping both the development and treatment of phobias.