Habituation, Sensitization, and Classical Conditioning Notes

Definition of Learning

• Learning is defined as a relatively permanent change in behavior resulting from experience.

Basic Learning Processes

• Habituation
• Sensitization
• Classical conditioning
• Operant conditioning
• Observational learning

Habituation

• Habituation is a fundamental form of learning.
• Example: A snail withdrawing its head in response to rain.
• Repeated rain leads to repeated head withdrawals.
• Habituation occurs when the snail stops withdrawing its head when it rains because it learns that the tapping on its shell is not threatening, as no negative consequences occur.

Habituation & Sensitization

• Response level fluctuates through trials.
• Initial orienting (noticing) response.

Sensitization

• Repeated presentation of a stimulus can result in a gradual increase in response intensity.
• Example: Repetition of a painful stimulus may increase the aversiveness of a loud noise.

Habituation

• Repeated presentation of a stimulus results in a gradual decrease in response intensity.
• Example: Repeatedly hearing a favorite song results in it becoming less enjoyable.

Classical Conditioning (Pavlovian Conditioning/Respondent Conditioning)

• Pioneered by Ivan Pavlov.

Stages of Classical Conditioning

1. Before conditioning: Unconditioned stimulus (US) elicits an unconditioned response (UR).
2. During conditioning: A neutral stimulus (NS) is presented along with the US, eventually becoming a conditioned stimulus (CS).
3. After conditioning: The CS elicits a conditioned response (CR), which is a learned response.

Association is created during conditioning.

Example

1. Before conditioning: US (food) -> UR (salivation).
2. During conditioning: US (food) -> UR (salivation), NS (bell).
3. After conditioning: CS (bell) -> CR (salivation).

Classical Conditioning Examples

• Taste aversion
• Allergic reactions
• Nocturnal enuresis

Nocturnal Enuresis Example

1. Before conditioning: US (bladder cues) -> UR (arousal - inhibition of urge).
2. During conditioning/training: US (loud noise) -> UR (arousal - inhibition of urge), NS (bladder cues).
3. After conditioning/training: CS (bladder cues) -> CR (arousal - inhibition of urge).

• Treatment involves using a noise or mild electric shock when bladder cues are detected.

Key Technical Terms

• Acquisition: The pairing of the NS and US leading to the NS becoming the CS and eliciting the CR. [Trapold \& Spence (1960)]
• Extinction: Following acquisition, if the CS no longer predicts the US, the CR reduces. [Pavlov (1927)]
• Spontaneous Recovery: After extinction, a pause before the next extinction process may lead to a partial recovery of the CR. [Pavlov (1927)]

Extinction

• The conditioned stimulus (CS) occurs in the absence of the unconditioned stimulus (US).
• Response amplitudes decrease in each session but recover a little between sessions.
• Repeated exposure to CS without US reduces the CR intensity.
• Example: Fear of hospitals can spontaneously recover after a break, even if nothing aversive occurs during visits.

Basic Procedure of Classical Conditioning

• US = unconditioned stimulus (e.g., food)
• UR = unconditioned response (e.g., salivation to food)
• CS = conditioned stimulus (e.g., bell – initially only orienting response)
• CR = conditioned response (e.g., salivation to bell)
• After a few conditioning trials, the conditioned response occurs BEFORE the food is presented.

Determinants of Strong Conditioning

• Temporal contiguity between CS & UCS
• Reliability of CS as predictor of UCS (contingency)
• Number of pairings of CS & UCS
• Intensity of CS & UCS affect intensity of CR
• Salience of CS
• Redundancy of CS (see Blocking effect; Kamin, 1969).
• CS-US Belongingness (e.g., evolved stimulus-response compatibility).

Timing in Classical Conditioning

• If a CS reliably predicts the US (good contingency), it will become excitatory.
• If a CS predicts the absence of a US (no contingency with a US), it will become inhibitory.

Blocking Effect (Kamin, 1969)

• The conditioned light function (i.e., fear) ‘blocks’ the acquisition of conditioned effects by the tone.
• The tone becomes redundant – it does not predict anything useful for the animal better than light does.

CS-US Belongingness

• Not all CS and US are easily associable. There are biological constraints on learning.
• Garcia & Koelling (1966) demonstrated this concept.

Higher Order Conditioning

1. Before conditioning: US (car crash) -> UR (fear).
2. During conditioning: US (car crash) -> UR (fear), NS (car).
3. After conditioning: CS (car) -> CR (fear).

• Involves the establishment of a new autonomous CS2-CR association in which the CS2 predicts a CR (such as fear).

Higher Order Conditioning (cont.)

1. First order conditioning (already occurred): CS1 (car) -> CR1 (fear).
2. During second order conditioning: CS1 (car) -> CR1 (fear), NS (garage).
3. Second order / higher order conditioning: CS2 (garage) -> CR2 (fear).

Sensory Preconditioning

1. Sensory preconditioning: NS1 (Sight of Person 1) - NS2 (Sight of Person 2) (learned).
2. During conditioning: NS2 (Person 2 near contact) -> UR (Emotional reaction).
3. After conditioning: CS (Sight of Person 1) -> CR (Emotional reaction).

Sensory Preconditioning (cont.)

1. Sensory preconditioning (already occurred): NS1 (Sight of Person 1) - NS2 (Sight of Person 2) (learned).
2. After conditioning (already occurred): CS1 (Sight of Person 2) -> CR (Emotional reaction).
3. New combined outcome of conditioning: CS2 (Sight of Person 1) -> CR (Emotional reaction).

• Higher order conditioning involves the establishment of a new CS2-CR (stimulus-response) association, whereas sensory preconditioning involves a new CS2-CS1 (stimulus-stimulus) association.
• Higher order conditioning typically produces stronger conditioning than sensory preconditioning.

Placebo Effects

1. Before conditioning: US -> UR
2. US (heroin) -> UR (pleasure: analgesia, sedation, euphoria), NS (injection ritual)
3. CS (injection ritual) -> CR (pleasure)

Classical Conditioning & Heroin Use

1. US (heroin) -> UR (pleasure: analgesia, sedation, euphoria)
2. CS (injection ritual) -> CR (pleasure)

Aversion Therapy (Counter-conditioning): Treatment of Alcoholism

1. History of conditioning involving alcohol: US (alcohol) -> UR (euphoria & pleasure), CS (sight/smell/taste of alcohol) -> CR (euphoria & pleasure).
2. Treatment involving novel conditioning: CS (sight/smell/taste of alcohol) -> CR (euphoria & pleasure), US (disulfiram - “Antabuse”) -> UR (nausea).
3. After conditioning: CS (sight/smell/taste of alcohol) -> CR (nausea/aversion).

Phobia: The Case of Little Albert (Watson & Rayner, 1920)

1. Before conditioning: US (loud noise) -> UR (fear/distress)
2. During conditioning: US (loud noise) -> UR (fear/distress), NS (rat)
3. After conditioning: CS (rat) -> CR (fear/distress)

Classical Conditioning: Generalisation

• CR occurs in response to CSs somewhat less like the original CS
• Generalization Curve: Strong CR near original CS, weakening as CS becomes more different.

Classical Conditioning: Discrimination

• CR increasingly occurs in response to CSs more similar to the original CS
• Discrimination Curve: CR is strong for CS similar to the original, weak for dissimilar CS.