Conditioned Taste Aversion

Introduction

Conditioned taste aversion is a unique form of classical conditioning.
It involves a learned avoidance of a particular taste following nausea.
Example given: Sherry's aversion to pizza after a stomach bug, despite pizza not causing the illness.

Unconditioned Stimulus (US): Automatically triggers a response (e.g., meat makes dogs drool, stomach bugs cause nausea).
Unconditioned Response (UR): The automatic response to the US.
Conditioned Stimulus (CS): A stimulus paired with the US, eventually triggering the response on its own (e.g., bell, pizza).
Conditioned Response (CR): The learned reaction to the CS.
Traditional rules of classical conditioning:
- Multiple pairings of CS and US are necessary.
- CS and US must be presented together in time.

Breaks traditional classical conditioning rules:
- Can occur with a single pairing.
- CS (food) and US (illness) do not need to be temporally close.
Often observed in cases of food poisoning and illness.

Named after John Garcia who studied this phenomenon.
Garcia's experiment:
- Rats conditioned to avoid sweet taste after pairing with radiation that causes nausea.
- Six groups: different irradiation levels and types of water (regular, saccharin).
- Rats preferred saccharin unless paired with radiation.
- Aversion lasted up to 60 days.

Garcia tested different conditioned stimuli (sweet taste, light, noise) with nausea (x-rays) and pain (electric shocks).
Findings:
- Taste (sweet) more easily associated with nausea.
- Sight and sound more easily associated with fear.

Challenges universal perspective of associative learning (Skinner, Pavlov).
Suggests evolutionary basis for taste aversion:
- Important to quickly associate taste and smell with potential harm.
Practical applications: Deterring predators using taste aversion (e.g., lithium chloride-treated carcasses).

Conditioned taste aversion is a strong, evolutionarily adaptive mechanism.
It helps prevent consumption of harmful substances by associating taste with illness.