🥯Learning Unit 2 – Classical Conditioning – Pavlov's Contributions

Key Concepts and Definitions

• Classical conditioning: learning process that occurs when a neutral stimulus is paired with a stimulus that naturally produces a response
• Unconditioned stimulus (US): stimulus that automatically triggers a response without any prior learning (food)
• Unconditioned response (UR): unlearned, automatic response to the unconditioned stimulus (salivation)
• Conditioned stimulus (CS): previously neutral stimulus that comes to trigger a response after being paired with the unconditioned stimulus (bell)
• Conditioned response (CR): learned response to the conditioned stimulus that is similar to the unconditioned response (salivation to bell)
  • Occurs after repeated pairings of the CS and US
• Acquisition: initial stage of learning where the association between the CS and US is formed and strengthened
• Extinction: gradual weakening and disappearance of the conditioned response when the CS is repeatedly presented without the US

Historical Context

• Ivan Pavlov (1849-1936) was a Russian physiologist who studied digestive processes in dogs
• Pavlov noticed that dogs began salivating before food was actually delivered, suggesting a learned association
• Pavlov's work on conditioned reflexes laid the foundation for the study of classical conditioning
  • Demonstrated that neutral stimuli could acquire the ability to elicit responses through association
• Pavlov's research was influenced by the work of other physiologists and psychologists of his time (Vladimir Bekhterev, Edward Thorndike)
• Pavlov's findings had a significant impact on the development of behaviorism, a major school of thought in psychology
• Classical conditioning became a cornerstone of behavioral psychology and influenced theories of learning, behavior modification, and therapy
• Pavlov's work earned him the Nobel Prize in Physiology or Medicine in 1904

Pavlov's Experimental Setup

• Pavlov used dogs as experimental subjects to study digestive processes and conditioned reflexes
• Dogs were restrained in a harness and had a small tube surgically implanted in their cheeks to measure salivation
• The experimental apparatus allowed Pavlov to present various stimuli and measure the dogs' salivary response
• Initially, Pavlov presented food (US) to the dogs, which naturally triggered salivation (UR)
• Pavlov then introduced a neutral stimulus, such as a bell (CS), before presenting the food
  • The bell was rung a few seconds before the food was given
• After several pairings of the bell and food, the dogs began to salivate in response to the bell alone (CR)
• Pavlov systematically varied the timing and presentation of stimuli to study the factors influencing conditioning

Components of Classical Conditioning

• Unconditioned stimulus (US): biologically potent stimulus that naturally triggers a response (food, loud noise)
• Unconditioned response (UR): automatic, unlearned reaction to the US (salivation, startle reflex)
• Conditioned stimulus (CS): initially neutral stimulus that comes to elicit a response after being paired with the US (bell, tone)
• Conditioned response (CR): learned reaction to the CS that resembles the UR (salivation to bell)
• Temporal contiguity: CS and US must occur close together in time for conditioning to occur
  • Optimal interval between CS and US is typically a few seconds
• Contingency: probability of the US occurring in the presence of the CS compared to its absence
  • Higher contingency leads to stronger conditioning
• Stimulus generalization: tendency for stimuli similar to the CS to elicit the CR (tones of similar pitch)

Process and Stages

• Acquisition: gradual development and strengthening of the conditioned response through repeated CS-US pairings
  • Number of pairings required for acquisition varies depending on the stimuli and organism
• Extinction: gradual weakening and disappearance of the CR when the CS is repeatedly presented without the US
  • Occurs when the CS no longer predicts the occurrence of the US
• Spontaneous recovery: reappearance of the extinguished CR after a period of rest without exposure to the CS
  • Demonstrates that extinction does not erase the original learning
• Stimulus discrimination: ability to distinguish between stimuli and respond differently to the CS and other similar stimuli
• Higher-order conditioning: a previously conditioned stimulus (CS1) can serve as a US for a new CS (CS2)
  • Allows for the formation of complex chains of associations
• Latent inhibition: prior exposure to the CS without the US can slow down subsequent conditioning
  • Familiarity with the CS reduces its associability with the US

Types of Conditioning

• Delay conditioning: CS is presented first and remains on until the US is delivered
  • Most common type of conditioning procedure
• Trace conditioning: CS is presented and terminated before the US is delivered
  • Requires a "trace" memory of the CS to bridge the gap between the stimuli
• Backward conditioning: US is presented before the CS
  • Generally less effective than forward conditioning (CS before US)
• Simultaneous conditioning: CS and US are presented at the same time and terminate together
  • Typically produces weaker conditioning compared to delay or trace procedures
• Temporal conditioning: organisms can learn to respond based on the passage of time alone
  • Conditioned response occurs at a specific time interval after the CS
• Sensory preconditioning: association between two neutral stimuli (CS1 and CS2) can be formed before either is paired with a US

Real-World Applications

• Taste aversion: association between a food (CS) and illness (US) can lead to avoidance of that food
  • Can occur even with long delays between the CS and US (hours)
• Phobias and anxiety disorders: learned fear responses to specific stimuli (animals, heights) through classical conditioning
  • Treatment often involves exposure therapy to extinguish the conditioned fear response
• Drug tolerance and withdrawal: repeated use of a drug (US) can lead to compensatory responses (CR) that oppose the drug's effects
  • Withdrawal symptoms are a manifestation of the CR in the absence of the drug
• Advertising and marketing: pairing a product (CS) with positive stimuli (attractive models, pleasant music) to create favorable associations
• Placebo effect: learned association between a placebo treatment (CS) and a physiological response (pain relief, improved mood)
  • Demonstrates the power of classical conditioning in shaping subjective experiences

Limitations and Criticisms

• Classical conditioning is a relatively simple form of learning that does not account for more complex cognitive processes
  • Does not explain how organisms learn novel behaviors or solve problems
• Conditioning is not always adaptive and can lead to maladaptive behaviors (phobias, superstitions)
• The role of biological preparedness and evolutionary history in conditioning is not fully addressed by the traditional model
  • Some stimuli are more readily associated with certain responses due to evolutionary significance (taste aversion)
• Classical conditioning does not consider the influence of motivation, attention, and individual differences in learning
• The strict temporal and contingency requirements of classical conditioning may not always hold in real-world situations
  • Learning can occur with longer delays or partial reinforcement schedules
• Later research has shown that animals can learn about the predictive relationships between stimuli (Rescorla-Wagner model)
  • Challenges the idea that conditioning is solely based on contiguity and repetition