Ivon Pavlov's study

Scenario 1: The Workplace Performance Review

Every time Marcus is called into the executive conference room, his manager gives him a severe reprimand about his performance, causing his heart rate to spike and his stomach to knot up in distress. Lately, whenever Marcus simply walks past the executive conference room on his way to the breakroom, his heart rate spikes and his stomach knots up.

• Unconditioned Stimulus (UCS): Severe reprimand / harsh confrontation

• Unconditioned Response (UCR): Heart rate spike and stomach distress (due to the reprimand)

• Conditioned Stimulus (CS): The executive conference room

• Conditioned Response (CR): Heart rate spike and stomach distress (due to the room alone)

Scenario 2: The Chemotherapy Room

A chemotherapy drug administered to a patient naturally induces severe nausea. Before every treatment, the nurse gives the patient a distinctly flavored lemon-lime drink to swallow the pills. After several treatment sessions, the patient begins feeling severely nauseous merely at the sight or taste of any lemon-lime flavored drink.

• Unconditioned Stimulus (UCS): Chemotherapy drug

• Unconditioned Response (UCR): Nausea (caused by the drug)

• Conditioned Stimulus (CS): Lemon-lime drink

• Conditioned Response (CR): Nausea (triggered by the drink)

Scenario 3: The Ocean Wave

A swimmer gets caught in a sudden, powerful rip current that pulls them underwater, causing a surge of terror and adrenaline. Right before being pulled under, the swimmer heard a loud, high-pitched lifeguard whistle blowing repeatedly. Months later, while sitting safely on a dry beach, hearing a distant high-pitched referee whistle during a volleyball game triggers an immediate surge of anxiety and adrenaline.

• Unconditioned Stimulus (UCS): Being pulled underwater / danger of drowning

• Unconditioned Response (UCR): Terror and adrenaline surge (from near-drowning)

• Conditioned Stimulus (CS): High-pitched whistle sound

• Conditioned Response (CR): Anxiety and adrenaline surge (from the whistle sound)

Part 2: How Conditioned Behaviours Are Unlearned

Conditioned responses are not permanent. They fade, reappear, or adapt based on changes in the environment through two key processes: Extinction and Spontaneous Recovery.

[Acquisition Phase]  --> CS + UCS repeatedly paired  --> CR established
[Extinction Phase]   --> CS presented ALONE          --> CR gradually weakens and disappears
[Pause Period]       --> Time passes without the CS
[Spontaneous Rec.]   --> CS suddenly presented again --> CR reappears temporarily (weaker)

1. Extinction

• What it is: The gradual weakening and ultimate disappearance of a conditioned response ($CR$) when the conditioned stimulus ($CS$) is repeatedly presented without the unconditioned stimulus ($UCS$).

• Pavlov's Example: If Pavlov repeatedly rang the bell ($CS$) but never gave meat powder ($UCS$), the dogs salivated less and less each time until they eventually stopped salivating altogether.

• Human Example: In exposure therapy for phobias, a person afraid of elevators ($CS$) spends time inside a safe elevator repeatedly without experiencing any harmful event ($UCS$). Over time, their fear reaction ($CR$) extinguishes.

2. Spontaneous Recovery

• What it is: The sudden reappearance of a previously extinguished conditioned response ($CR$) after a rest period or passage of time, without any new conditioning.

• Pavlov's Example: After extinguishing the salivation response completely, Pavlov rested the dogs for a few days. When he rang the bell again for the first time, the dogs salivated again—though not as strongly as before.

• Key Insight: Extinction does not erase the original learning; it simply suppresses or masks it. The brain retains a memory trace of the original association.

Summary of Extinction vs. Spontaneous Recovery

Concept	Action	Result
Extinction	Present $CS$ continuously without $UCS$.	Response ($CR$) gradually vanishes.
Spontaneous Recovery	Reintroduce $CS$ after a period of rest.	Extinguished response ($CR$) briefly resurfaces.