Taste Aversion

Modified: 2024-07-02 12:05 AM CDST

• Garcia was studying classical conditioning in rats.
  • Nausea was the UCR, and it was induced by two UCSs, either X-rays or LiCl (a salt).
  • Both of the UCSs will cause nausea in the appropriate dosage.
  • Other groups of rats were given electric shock as a UCS.
  • The CSs were either bitter water or plain water associated with light and sound.
  • So, some rats drank the bitter water and were made sick.
  • Others drank the bitter water and received a shock. Still others drank the plain water and were made sick.
  • Finally, some drank the plain water and received an electric shock.

• Then all were allowed to choose between the bitter water and the plain water associated with the light and sound.
  • Those that had been made sick would not drink the bitter water.
  • One group would not drink even when the interval between the bitter water and the nausea had been 75 minutes!
    • Talk about trace conditioning.
  • The rats that had received the foot shock did not avoid the water in either form.
• The main result of Garcia's research was to demonstrate that not all CS-UCS pairings are equivalent.
  • This was a blow to established learning theory (More recent research has shown that nearly any CS can be made to act like the bitter water.
  • However, the procedures to do so are different than Garcia's, so the effect of Garcia's research remains.)
• In a practical sense, a new field emerged, one that studies taste aversions.
  • For example, suppose you have never eaten oysters.
    • You arrive in New Orleans, are persuaded to try a dozen raw ones, but one was bad.
    • Your next three days are spent retching.
    • What will you do if, three months later, someone offers you an oyster? Will you recall your bad experience in New Orleans? Will you eat raw oysters again?
    • This phenomenon is related to food neophobia, the fear of new foods.
    • We are much more likely to become conditioned to the UCSs and UCRs associated with new foods than to old foods.
  • So, if you were a longtime raw oyster eater and ate a bad one, you will probably eat oysters again.
• Finally, a very real problem is the issue of pest control.
  • Coyotes have thus far resisted all efforts at control, including poisoning.
    • Poison baited carcasses have been set out in an attempt to reduce their numbers.
    • The coyotes very quickly learn to avoid such baits.
    • Why? If they only eat enough to become sick, they learn to avoid such new food sources.
  • The same is true with rats. They will learn to avoid poison baits for the same reason.

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