In behavioral psychology, an unconditioned response is a response to an unconditioned stimulus that is automatic. It is neither taught nor learned. It is the opposite of a conditioned response which is learned through training and repetition.
Unconditioned responses, such as twitching, sneezing, yawning, salivating at food, and eye watering are natural reactions of our bodies that help protect us from potential dangers.
The concept comes from the classical conditioning approach within the behaviorist theory of psychology. The concept was first identified by Ivan Pavlov whose famous Pavlov’s dog experiment showed an unconditioned response in a dog who smelled food.
Examples Of Unconditioned Response
1. Flight Response (After seeing a Threat)
Stimulus: A threat to your life
Response: To run away
The fight-or-flight response is a response humans and other animals naturally have when they come across a threat. This is a physiological response that is activated in emergency situations, like a speeding truck or a baseball about to hit you in the face.
The reaction happens immediately, like a reflex. The reflex might be activated even before you are consciously aware of what is happening. For example, if you are walking in the forest and a bear jumps out from the bushes, you will likely take off running before your brain has had enough time to label the animal as “a bear”.
In these situations, the truck, baseball, and bear are examples of an unconditioned stimulus (UCS), and the flight-or-fight response is the unconditioned response (UCR).
2. Scratching (After an Itch)
Stimulus: An itch
Response: A scratch
Every itch needs to be scratched. Not scratching can literally drive you crazy. Feeling itchy can be caused by several different reasons. For example, when the skin is dry it can become flaky and small particles may disconnect from the larger skin membrane.
When that happens, very specific nerves in the skin are activated and send a message to the brain. The message is interpreted as “itchy” (unconditioned stimulus), which then generates scratching (unconditioned response).
There are other causes of feeling itchy. For example, when an insect like a mosquito or parasite lands on your skin, it can feel itchy and compel a person scratch. This is a very adaptive response that could prevent illness or an infection caused by a bite.
3. Mouth Watering (At the Smell of Delicious Food)
Stimulus: Smell of Tasty Food
Response: Mouth Watering
The smell of delicious food can trigger a mouth-watering reaction. We start producing saliva in anticipation of the food that may (or may not!) be entering our mouth shortly.
In fact, mouth-watering was the first unconditioned response identified by Ivan Pavlov when he conducted his Pavlov’s dog experiment. Pavlov noticed that his dog’s mouth would water whenever he entered to give it food.
Pavlov later turned this into a conditioned stimulus and response when he taught his dog to salivate whenever he rang a bell before feeding the dog. Here, the dog’s salivation was a learned reaction to a rining bell – it wasn’t innate, but had to be taught through repetition.
4. Sneezing (When you get Dust in your Nose)
Stimulus: Dust in Nose
When dust enters your nose, you are likely to sneeze. Here, the dust in the nose is the unconditioned stimulus and sneezing is the unconditioned response.
We sneeze because our body tells us that we need to expel the unknown agent (dust) in our bodies. This response is innate and natural to humans. It’s not something we learn or are taught to do, so it’s not a conditioned response. Rather, it’s a response that just feels natural.
In the past, sneezing was seen as a way to expel demons from our bodies (hence the refrain “bless you” when you sneeze). But today, we know it’s simply physiology that’s there to protect our lungs!
5. Eye Watering (When Dicing Onions)
Stimulus: Onion Juice
Nothing will happen if you hold an onion near to your face and close it. Even though onions are known for causing tears, this only happens when we’re cutting them.
When you cut an onion, a variety of chemicals are released into the air. The eye is irritated by these compounds, causing it to water in order to clean itself out. This is the natural response of the eyes to an irritant, therefore it is known as an unconditioned response rather than a conditioned response.
6. Nausea (At the Sight of Vomit)
Stimulus: Sight of Vomit
When someone vomits, our bodies often instantly react with nausea. We might feel sick in our own stomachs and react by gagging.
This is likely because the sight, sound, and smell of vomit evokes memories of times when we were sick. Thus, we do not intentionally or even willingly feel nauseous at the sight of vomit. Rather, our body’s subconscious reaction is to feel sick and revulsed by it.
Many nurses who spend a lot of time around sick people may lose this unconditioned response. In these cases, they have experienced a phenomenon called ‘systematic desensitization’ where they have over time become desensitized to an unconditioned stimulus.
7. Wincing (After Stubbing Your Toe)
Stimulus: Stubbing a Toe
Wincing is an unconditioned response that occurs when we experience pain. It’s literally our body curling itself up in order to shut itself off from new potential sources of pain.
Furthermore, the wince can act as a warning sign to nearby members of our tribe to let them know of potential danger. Scientists have observed it in other animals such as rats, rabbits, horses, and sheep.
8. Active Immune System (After Infection)
Stimulus: Infections in the body
Response: Spike in immune response
If you have an infection, then your immune system will automatically be activated. It will immediately start to attack the infection with the various cells that make up the immune system.
This reaction does not require any learning. It happens automatically. Therefore, we can say that the infection is the unconditioned stimulus and the immune system’s response is the unconditioned response.
Of course, there are numerous factors that impact the effectiveness of the immune system’s response. The person’s physical health, their diet, in addition to the number and potency of the viral cells, just to name a few. However, the response will still occur and that is what makes it an unconditioned response.
9. Universal Emotion of Sadness (After Loss)
Stimulus: Loss of a loved one
For many decades now, psychologists and anthropologist have studied human emotions. People from all over the world share some of the most fundamental emotions. For example, emotions such as sadness, anger, fear, and disgust are felt in very similar ways in response to the same stimuli.
Tell a person in any culture about the loss of a loved one and they will feel sadness. Even in cultures that frown upon public displays of emotions, the same underlying affective state will occur as in a person from a more open culture. The facial expression might be harder to see, but the emotion is there.
The situation described (unconditioned stimulus) will illicit the same emotional reaction (unconditioned response) no matter where a person was born or the kind of culture they live in.
10. Giggling (After Tickling)
When we are tickled, we usually laugh uncontrollably. The stimulus in this situation (tickling) leads to an unconditioned response: giggling.
Scientists believe that this unconditioned response occurs because tickling triggers a flight or fight response, and the ‘flight’ response in this situation is not running, but giggling. The giggle acts as a sign of submission that helps the tickler know you’re not a threat. The alternative reaction – fight – would likely be to literally fight back against the person tickling you!
11. The Moro Reflex
Stimulus: Putting a baby on its back
Response: An appearance of being startled
Babies do something very peculiar as newborns. When a parent lays them down to sleep on their backs, they will often act startled. Their eyes will get very big and their arms and legs will branch out as if they were falling. This is called the Moro reflex. It is named after the Austrian physician, Ernst Moro, that first described it in 1918.
Although seeing their baby have this reaction can make a lot of parents feel like they have done something wrong, it is actually a sign of healthy neurological development. In fact, most hospitals will test for this reflex within the first month after birth.
If we look at the situation from a classical conditioning perspective, then being put down to sleep on the back is the unconditioned stimulus, and the Moro reflex is the unconditioned response.
12. Stress Response
Stimulus: A stressful life situation
Response: Rising blood pressure and anxiety
Modern life is very stressful for a lot of people. There are numerous pressures to deal with on a daily, and sometimes, minute-by-minute basis. Some jobs are extremely stressful, like being a surgeon or nurse.
Unfortunately, the human body was not really built to deal with frequent pressure. Our bodies are hard-wired to handle emergency situations, like threats of life and death, which may happen occasionally.
But since the industrial revolution, life has become quite hectic. When we experience the stress of meeting deadlines, being stuck in traffic, or paying bills, our body has a small fight-or-flight response.
That may sound harmless enough, but over time it can lead to serious health issues and has even been linked to cardiovascular disease. The pressures of modern life (unconditioned stimulus) create too much stress in our lives (unconditioned response).
13. The Gag Reflex (After a Swab)
Stimulus: A cotton swab in the mouth
Some medical tests for diagnosing infections involve a medical professional inserting a cotton swab in the patient’s mouth. The swab has to go fairly far back into the oral cavity. It is then swept along the back to pick up a sample for testing.
This can generate the gag reflex, a sudden contraction of the back of the throat. It happens involuntarily and can be triggered by an object touching the back of the tongue, the tonsils, or the back of the mouth.
Because it happens involuntarily in response to an object, it can be explained by CC. The cotton swab is the unconditioned stimulus and the gag reflex is the unconditioned response.
14. Oxytocin Release (After Hugging)
Stimulus: A hug
Response: Oxytocin release
Hugging and touching, when appropriate, can have surprisingly powerful effects on our health and well-being. There is in fact, a physiological basis for these effects. When being hugged by someone that we care about, the brain increases levels of the hormone oxytocin.
This hormone makes us feel good and is also involved in childbirth and breastfeeding. When released during these moments it facilitates bonding between mother and baby. Therefore, it has a great deal of value for the survival of the species.
Hugging can also help us when we feel sad or depressed. Because hugging (unconditioned stimulus) will release oxytocin (unconditioned response), someone feeling quite sad will start to feel better. Even if that feeling is for just a few minutes, that hug might come at just the right time.
15. Startle Response (After Thunder)
Response: A startled jump
The startle response is a dramatic physical reaction to a sudden intense stimulus. The stimulus could be a loud noise, such as thunder, or a bright flash of light, such as lightning. In humans, these events will create an automatic physical and mental reaction.
The physical reaction can include a rapid contraction of the muscles in the arms and legs, along with an increase in blood pressure and respiration rate. The mental response often involves intense feelings of fear and nervousness.
In terms of CC, the sound of thunder or the flash of lightning are examples of a unconditioned stimulus, and the startle response of muscle contractions and fear are examples of an unconditioned response. Like many stimulus–response connections, the unconditioned response is considered highly adaptive and has played a significant role in the survival of the species.
16. Micro Expressions
Stimulus: Being accused of lying
Response: Brief facial expression or ‘tic’
A micro expression is a facial expression that reveals our inner emotional state. It happens incredibly fast, lasting less than ½ a second. Sometimes a microexpression is the result of a voluntary, controlled repression.
For example, a person may be trying to hide something, but the real emotion slips out. It happens involuntarily. The person can’t really control the display and may not even be aware of it.
The ability to recognize and accurately interpret micro-expressions has many applications, especially in law enforcement. Every year, thousands of FBI agents and police officers participate in microexpression training. When questioning a suspect, an officer will ask a probing question (unconditioned stimulus), and if the suspect is trying to hide the truth, they might display a microexpression (unconditioned response).
Unconditioned Response in Classrooms
Teachers can use the unconditioned response concept in the classroom for behavior management. Below are some great examples.
1. Turning down the Fan
Stimulus: Turning down the fan
Response: Students lower their noise
My high school physics teacher taught me this trick, and I use it on my own students to this day! If she wanted the class to lower the noise level, she would quietly walk over to the fan and turn it off. The falling ambient noise acts as a subconscious cue to students that they, too, should lower their voice to match the new noise level.
This was far more affective than yelling over the students to keep their voices down, and worked every time!
2. The ‘Teaching Spot’
Stimulus: Teacher stands in their teaching spot
Response: Students go silent
In teacher training, we often show teachers the trick of having a ‘teaching spot’. This teaching spot is one location in the classroom where the teacher always stands when they want the class’s attention. They might start all lessons from that spot, and use the same spot every time they need the class to quieten down and pay attention.
Over time, when the teacher moves to the teaching spot, it becomes a subtle message to the students to pay attention. The teacher never needs to be explicit about this – it just happens over time and through subtle repetition.
3. Prolonged Silence
Stimulus: Prolonged silence from teacher
Response: Class looks at teacher
Nearly everyone would have a memory of a teacher staring at them as if they were boring a hole in the head. The teacher just stands there and stares intently – usually with a condescending look on their face – until the student stops talking and pays attention.
Here, we’re never taught that this look means we need to be quiet. Rather, the look on the teacher’s face – their sternness and anger – makes us go quiet.
The same happens in a whole class situation. The teacher stands in front of the class and just waits. No teaching occurs – nothing. The classmates tap each other on the shoulder and shush one another until, finally, all is quiet. Then, the teacher starts talking.
Related Theoretical Concepts
- Stimulus Discrimination – The capacity to differentiate between various types of stimuli and respond appropriately.
- Stimulus Generalization – This occurs when an unconditioned response is elicited by a stimulus that is similar, but not identical, to the original conditioned stimulus.
- Operant Conditioning – Conditioning that relies upon explicit teaching, positive reinforcement, negative reinforcement, and punichment.
When Pavlov conducted his experiments on the digestive juices of dogs, no one could have imagined the ramifications of his findings. The principles of classical conditioning have had a tremendous impact in so many ways, from academic studies to explanations for everyday phenomena.
Understanding the unconditioned response has been particularly enlightening. For example, the unconditioned response helps us escape from immediate danger or prevent being bitten by a disease-carrying mosquito.
Generating an unconditioned response is why mothers feel so joyous after giving birth and bond with their newborn. The response of a hug can help us feel better at some of the worst moments of our lives. While understanding the unconditioned response of micro expressions can help law enforcement catch criminals. Without a doubt, the unconditioned response is a key reason human beings have survived for so long.
Cunningham, M.R. (1986). Measuring the physical in physical attractiveness: quasi-experiments on the sociobiology of female facial beauty. Journal of Personality and Social Psychology, 50, 925-935.
Elvitigala D.S., Boldu R., Nanayakkara S.C., and Matthies D.J.C. (2022, January 14). TickleFoot: Design, Development and Evaluation of a Novel Foot-Tickling Mechanism That Can Evoke Laughter. ACM Transactions on Computer-Human Interactions. 29, 3. pp 1–23. https://doi.org/10.1145/3490496
Pavlov, I.P. (1927). Conditioned reflexes. London: Oxford University Press.
Singh, D. (1993). Adaptive significance of female physical attractiveness: role of waist-to-hip ratio. Journal of personality and social psychology, 65(2), 293.
Yim JongEun. (2016). Therapeutic benefits of laughter in mental health: A theoretical review. The Tohoku Journal of Experimental Medicine 239, 3 (2016), 243–249.