Non-Associative Learning

What is Non-Associative Learning?

Non-associative learning refers to changes in behaviour due to repeated exposure to a single stimulus.

There are two major forms: habituation and sensitisation.

Habituation

Definition:
A progressive decrease in response to a repeated stimulus.

Features:

• Response decreases with repeated exposure
• Stimulus-specific
• Helps tune out irrelevant or non-threatening stimuli
• Can be short-term or long-term
• Response can be recovered (not due to sensory fatigue)

Examples:

• Stopping noticing a ticking clock
• Taste of food decreasing across repeated bites
• Becoming used to background noise

Sensitisation

Definition:
An increase in response following repeated or intense exposure to a stimulus.

Features:

• Not stimulus specific (general arousal increases)
• Often a protective mechanism
• Used to anticipate important or threatening events
• Common examples: startle response, orienting response

Why it is not stimulus-specific:
Increasing arousal prepares the organism for multiple possible threats, not just the original stimulus.

Sensory Adaptation vs Habituation

These are not the same.

Feature	Sensory Adaptation	Habituation
Cause	Fatigue of sensory receptors	Learned decrease in response
Recovery	Cannot recover sensitivity immediately	Response can recover (dishabituation)
System	Peripheral (sensory organs)	Central (brain learning mechanism)

Dishabituation

Definition:
Recovery of a habituated response after a new or unexpected stimulus appears.

Example:
Becoming aware of the ticking clock again after someone coughs or an announcement is made.

Desensitisation

Definition:
A sensitised response gradually reduces back to baseline after repeated exposure.

Example:
Startle response to dogs licking you decreases over time.

Orienting Response

Orienting response: Movement of attention toward a novel or significant stimulus.

1985 Infant Study:

• Infants habituated quickly to a 4×4 grid (simple, low interest).
• Infants initially sensitised to a 12×12 grid (complex stimuli create initial arousal).
• After habituation, a tone was introduced → dishabituation occurred.

Conclusion: humans are wired to notice novelty.

Stimulus Intensity and Learning

Typical patterns:

Stimulus Intensity	Outcome
Low	Habituation
High	Sensitisation
Medium	Sensitisation → then habituation

Exception: Evolutionary significance
Some small/quiet stimuli (mosquito buzz, baby crying) trigger sensitisation due to biological importance.

Dual Process Theory

States that habituation and sensitisation occur simultaneously.

• Habituation process occurs in the S–R system (specific stimulus–response pathway).
• Sensitisation process occurs in the state system (general arousal system).

The outward behaviour is determined by which process is stronger at the moment.

Associative Learning

What is associative learning?

Associative learning is when we form links between two events that occur together. Over time, we learn that one event predicts another, and this shapes our behaviour.

Psychology studies two main types:

• Classical conditioning: learning that two stimuli go together.
• Operant conditioning: learning that a behaviour leads to a consequence.

In this week’s content, we are focusing only on the introduction to Classical Conditioning. See further notes for Operant Conditioning.

Classical Conditioning

Classical conditioning = learning through repeated pairing of a neutral stimulus (NS) with an unconditioned stimulus (US) to produce a conditioned response (CR).

Terminology

Term	Definition
NS (Neutral Stimulus)	Does not elicit the target response
US (Unconditioned Stimulus)	Naturally elicits a response
UR (Unconditioned Response)	Natural, unlearned reaction to the US
CS (Conditioned Stimulus)	Previously NS, now predicts US
CR (Conditioned Response)	Learned response to CS

Pavlov’s Dogs

• US = food
• UR = salivation
• NS = bell
• After pairing: bell → salivation
• CS = bell
• CR = salivation in absence of food

The Stages of Conditioning

1. Acquisition: CS–US pairings increase CR strength
2. Asymptote: Response plateaus
3. Extinction: CS presented alone → CR decreases
4. Spontaneous recovery: CR returns after rest period

Types of Unconditioned Stimuli

Type	Description
Appetitive	Desired, approach behaviour (food, water)
Aversive	Avoidance behaviour (shock, loud noise)

Aversive conditioning typically acquires faster.

Types of Conditioned Stimuli

Type	Description
Excitatory CS (CS+)	Predicts presence of US
Inhibitory CS (CS–)	Predicts absence of US

Stimulus Substitution Theory (Pavlov)

Proposed that the CS becomes a substitute for the US.

Supported by Jenkins & Moore autoshaping:

• Grain → pigeons pecked CS light
• Water → pigeons performed drinking motions

Also introduced:

• Sign trackers: Focus on CS
• Goal trackers: Focus on actual US

Sign tracking correlates with impulsivity and maladaptive behaviours.

Why Substitution Theory Is Incomplete

CR ≠ UR in many cases.

Example:

• US = shock → UR = jumping
• CS = tone → CR = freezing (preparatory defence)

Therefore, the CS does not always produce the same response as the US.

Preparatory Response Theory (Kimble)

CR prepares the organism for the expected US.

Example:
Salivation = preparation for food, not substitution for food.

Compensatory Response Theory

CR compensates for the aftereffects of the US to maintain homeostasis.

Example:
Body prepares for dryness of mouth → salivation increases when CS predicts food.

Variations of Classical Conditioning

First-Order Conditioning

Standard CS–US pairing (Pavlov).

Second-Order (Higher-Order) Conditioning

• CS1 is conditioned with US
• NS pairs with CS1 → becomes CS2
• CS2 produces CR (weaker)

CR to CS2 ≈ 50% strength of CS1.

Sensory Preconditioning

• Two neutral stimuli (NS1 + NS2) paired first
• Later, NS1 paired with US → becomes CS1
• NS2 also elicits CR due to earlier association

Order of associations differs:

• Sensory preconditioning: NS–NS first
• Second-order: CS–NS after conditioning

Limitations of Classical Conditioning

Limitation	Description
Overshadowing	Stronger stimulus overpowers weaker stimulus in compound conditioning
Blocking	Prior strong CS prevents learning of new CS
Latent inhibition	Familiar stimuli are harder to condition

Timing in Conditioning

Type	Feature	Effectiveness
Simultaneous	CS and US occur together	Weak conditioning
Delayed	CS precedes US briefly; overlap	Most effective (0.5–1 sec)
Trace	CS ends before US begins	Depends on memory; weaker as interval increases
Backward	CS appears after US	Very weak; CS predicts absence of US