Lecture 8: Learning – Classical and Operant Conditioning

Learning

Introduction to Learning

Learning is the process by which behavior or knowledge changes as a result of experience. In psychology, learning is often studied through the relationship between a stimulus (S) and a response (R). Key questions include whether learning is automatic, how it can be acquired, and what factors influence the increase or decrease of a response.

• Stimulus (S): Any event or object in the environment that elicits a response.

• Response (R): The behavior or reaction to a stimulus.

Classical Conditioning

Definition and Overview

Classical conditioning (also known as Pavlovian conditioning) is a type of learning in which an association is formed between a neutral stimulus (NS) and an unconditioned stimulus (US) to produce a conditioned response (CR).

• Unconditioned Stimulus (US): A stimulus that naturally and automatically triggers a response (e.g., food).

• Unconditioned Response (UR): The unlearned, naturally occurring response to the US (e.g., salivation).

• Neutral Stimulus (NS): A stimulus that initially produces no specific response.

• Conditioned Stimulus (CS): Previously neutral stimulus that, after association with the US, triggers a conditioned response.

• Conditioned Response (CR): The learned response to the previously neutral stimulus.

Pavlov's Dogs Example

• Food (US) → Salivation (UR)

• Food (US) + Metronome (NS) → Salivation (UR)

• Metronome (CS) → Salivation (CR)

Example: Pavlov demonstrated that dogs could learn to salivate at the sound of a metronome if it was repeatedly paired with food.

Little Albert Experiment

• Loud noise (US) → Fear response (UR)

• Loud noise (US) + White rat (NS) → Fear response (UR)

• White rat (CS) → Fear response (CR)

Example: In the Little Albert experiment, a child learned to fear a white rat after it was paired with a loud, frightening noise.

Processes of Classical Conditioning

• Acquisition: The initial phase of learning when a response is first established.

• Extinction: Reduction in the conditioned response (CR) when the conditioned stimulus (CS) is no longer paired with the unconditioned stimulus (US).

• Spontaneous Recovery: The reappearance of a previously extinguished conditioned response after a period of no exposure to the conditioned stimulus.

Example: After extinction, a dog may briefly salivate again to the metronome after some time has passed.

Operant Conditioning

Definition and Overview

Operant conditioning is a type of learning in which the relationship between a stimulus and response is influenced by the consequences of the response. This form of learning is associated with B.F. Skinner and involves reinforcement and punishment.

• Reinforcement: Any consequence that increases the likelihood of a behavior.

• Punishment: Any consequence that decreases the likelihood of a behavior.

Learning Through Consequences

• Behaviors can be shaped by their outcomes, such as rewards or punishments.

• Examples include addiction to gambling (reinforcement by wins) or compulsive behaviors (reinforcement by dopamine release).

Principles of Operant Conditioning

• Positive Reinforcement: Adding a pleasant stimulus to increase behavior.

• Negative Reinforcement: Removing an unpleasant stimulus to increase behavior.

• Positive Punishment: Adding an unpleasant stimulus to decrease behavior.

• Negative Punishment: Removing a pleasant stimulus to decrease behavior.

• Avoidance Learning: Behavior prevents the possibility of an unpleasant stimulus.

• Escape Learning: Behavior removes an unpleasant stimulus that is already present.

Example: A rat pressing a lever to receive food (positive reinforcement) or to stop a mild shock (negative reinforcement).

Processes of Operant Conditioning

• Primary vs. Secondary Reinforcers: Primary reinforcers satisfy biological needs (e.g., food), while secondary reinforcers are learned (e.g., money).

• Discriminative Stimulus: A cue indicating whether a response will be rewarded.

• Discrimination: Learning to respond only to a specific stimulus, not to similar ones.

• Generalization: Responding to new stimuli that are similar to the original discriminative stimulus.

Example: A rat learns to press a lever only when a light is on (discriminative stimulus).

Reinforcement Schedules

Reinforcement schedules determine how and when a behavior is followed by a reward or punishment. These schedules affect the rate and strength of learning.

Schedule Type	Description	Example
Fixed Ratio	Reinforcement after a set number of responses	Factory worker paid for every 10 items produced
Variable Ratio	Reinforcement after a variable number of responses	Slot machine payouts
Fixed Interval	Reinforcement after a set period of time	Weekly paycheck
Variable Interval	Reinforcement after a variable period of time	Checking for a randomly arriving email

Example: Variable ratio schedules tend to produce high rates of responding and are resistant to extinction.

Additional info: Dopamine pathways in the brain (e.g., nucleus accumbens and ventral tegmental area) are involved in reinforcement learning, influencing motivation and reward-seeking behavior.