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30 Examples of Unconditioned Response in Classical Conditioning

What Is Unconditioned Response

In the classical conditioning paradigm, an unconditioned response (UCR) is a natural, automatic response to a stimulus that does not require prior learning. Unconditioned responses are reflexive responses that occur involuntarily. These natural reactions can be emotional reactions or physical reactions​1​.

taping the kneecap

Classical Conditioning

Classical conditioning is a type of learning that was first introduced by Russian physiologist Ivan Pavlov during his experiments on the digestive systems in dogs.

He noticed that his dogs salivated at the presentation of food. Salivation in response to the sight of food was an unconditioned response. This natural response does not have to be learned or conditioned.

Then, he created a series of experiments in which he rang a bell whenever he brought food. Eventually, the dogs started salivating when they heard the bell alone, without seeing the food.

This classical conditioning process of associating a stimulus (the ringing) with a response (salivation) is, therefore also called Pavlovian conditioning.

The food was an unconditioned stimulus (UCS) that could elicit salivation, the unconditioned response (UCR). The ringing, which was initially a neural stimulus, became a conditioned stimulus (CS) that could also elicit salivation, now called the conditioned response (CR)​2​.

Unconditioned Response vs. Conditioned Response

Unconditioned responses are often contrasted with conditioned responses. 

The key difference between the two is that an unconditioned response is an unlearned response provoked by an unconditional stimulus, whereas a conditioned response is a learned response.

Unconditioned responses are innate responses that organisms have from birth, not acquired after birth. They are involuntary reflexes.

Associating a neutral stimulus with the unconditioned response results in a conditioned stimulus that can produce a conditioned response like the unconditioned response.

Therefore, unconditioned responses and conditioned responses may look the same, but they are produced by different types of stimuli​3​.

Unconditioned Response Examples

Here are some common examples of unconditioned responses in everyday life.

  1. A feeling of hunger in response to the smell of food.
  2. Reflexively close your eyes when an object comes too close to them.
  3. Screaming in pain after being hit unexpectedly.
  4. Gasping in response to surprise or shock.
  5. Twitching your leg in response to being tapped on the kneecap.
  6. Startled when there is a sudden loud noise.
  7. Stepping back when someone suddenly appears in front of you.
  8. Squirting, closing your eyes, or contracting facial muscles when tasting sour food.
  9. Gagging at the smell of spoiled food.
  10. Sneezing when stimulated by dust or other irritants.
  11. Yawning when feeling sleepy or bored.
  12. Vomiting in response to food poisoning.
  13. Sweating in response to anxiety.
  14. Rapid breathing when performing strenuous physical activities.
  15. Crying response in babies when they are hungry.
  16. Pupil dilation in low light levels.
  17. Blinking when a puff of air is blown into the eyes.
  18. Goosebumps in cold temperatures.
  19. Shivering when exposed to chills.
  20. Coughing on inhaling respiratory irritants.
  21. Blushing when embarrassed.
  22. Frowning when dissatisfied.
  23. Tensing of muscles when experiencing fear.
  24. Nausea from motion sickness.
  25. Crying when dicing onions.
  26. Dodging from a flying ball.
  27. Laughing at a funny joke.
  28. Flinching in response to an unexpected touch.
  29. Relaxation of muscles when listening to soft music.
  30. Clenching of fists when angry.
  31. Stomach growling when hungry.


  1. 1.
    Clark RE, Manns JR, Squire LR. Classical conditioning, awareness, and brain systems. Trends in Cognitive Sciences. Published online December 2002:524-531. doi:10.1016/s1364-6613(02)02041-7
  2. 2.
    Clark RE. The classical origins of Pavlov’s conditioning. Integr psych behav. Published online October 2004:279-294. doi:10.1007/bf02734167
  3. 3.
    Linnman C, Rougemont-Bücking A, Beucke JC, Zeffiro TA, Milad MR. Unconditioned responses and functional fear networks in human classical conditioning. Behavioural Brain Research. Published online August 2011:237-245. doi:10.1016/j.bbr.2011.02.045


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