Unit 4 · Learning Theory · Reading 5 of 13
Built-In Shortcuts: Taste Aversion and Higher-Order Conditioning
Before you read
Is there a food you won't eat because it once made you sick? How many times did it take before you started avoiding it?
Words you'll own by the end
- Conditioned taste aversion: a learned dislike of a food linked to getting sick.
- John Garcia: the researcher most associated with taste aversions.
- Biological preparedness: being built to learn some associations faster than others, because they help us survive.
- Higher-order (second-order) conditioning: a CS is paired with a new neutral stimulus, which then becomes a CS too.
1. Taste aversion breaks the rules
Classical conditioning also happens outside the lab. Say you eat fried clams at lunch. You've caught a virus, but it hasn't hit yet. At 6 p.m. you start vomiting. Even though the virus made you sick, your brain links the illness to the clams. Now just seeing fried clams makes you feel queasy. That's a conditioned taste aversion.
Taste aversions are unusual in two ways:
- One pairing is enough. Most conditioning takes repetition. This can happen after a single bad experience, and it can last for years.
- The UCS doesn't come right away. Hours passed between the clams and the vomiting, and you still made the link. Reading 2 said close timing matters, and taste aversion is the big exception.
Also notice the UCR and CR are different here. The UCR is vomiting. The CR is feeling nauseated. You probably won't actually throw up at the sight of clams.
Try it: Label the fried clams example
Use the five parts from Reading 2.
2. Why we're built this way
John Garcia is the researcher most associated with taste aversion. He and others argued it shows biological preparedness: we're predisposed to make certain connections quickly because they help us survive. If one bad meal can teach you to avoid a food for years, you're less likely to poison yourself twice.
Preparedness may also explain why phobias of snakes and heights are far more common than phobias of books or bicycles. Snakes and heights threatened our ancestors' survival; books never did.
Check-in: Why is a phobia of snakes more common than a phobia of bicycles?
3. Higher-order conditioning
Once a CS is learned, it can be used to teach a new CS. Say Pavlov's dogs already drool at the metronome. Now flash a red light right before the metronome, many times, with no food at all. Eventually the dogs drool at the red light alone. That's second-order or higher-order conditioning.
The red light was never paired with food, only with the metronome. Second-order conditioning is usually weaker and takes more pairings.
First-order vs. second-order
First order
Second order
The metronome takes the place of the food. No food is involved in this stage.
Check-in: A dog already drools at the sound of the can opener. The owner always opens the creaky pantry door right before using the can opener. Now the dog drools at the creak alone. What is this?
Am I ready for a pop quiz?
Check a box only if you can say the answer out loud without scrolling up.
Come back to your "before you read" question
Your food: did it take one bad experience? Did hours pass between eating it and feeling sick? If so, you lived Garcia's research.