Classical Conditioning: How It Works and Examples

Medically Reviewed by Zilpah Sheikh, MD on October 31, 2023
7 min read

Classical conditioning, also called Pavlovian conditioning or respondent conditioning, is learning through association. This behavioral learning method was first studied in the late 19th century by Russian physiologist Ivan Pavlov. 

Pavlov’s dog experiment

In the 1890s, Pavlov was experimenting with dogs, ringing a bell whenever they were fed. Over time, the dogs learned to associate a neutral stimulus (bell ringing) with a positive one (food). Pavlov also noticed that his dogs would often begin to salivate whenever they heard the footsteps of his assistant bringing them the food. This is called a conditioned response. Pavlov's experiment and its association between positive and neutral stimuli became the foundation of classical conditioning theory.

Eventually, Pavlov linked these behavioral associations to humans. He spent the remainder of his career studying the phenomenon.


To understand how classical conditioning works, it's helpful to understand the following terms.

  • Neutral stimulus. A stimulus is something that triggers a physical or behavioral change. A neutral stimulus produces no response. At first, Pavlov's dogs had no response to the bell.
  • Unconditioned stimulus. This is what leads to an automatic response. In Pavlov’s experiment, it's the food.
  • Unconditioned response. A normal process, like salivating when you smell food, is an unconditioned response.
  • Conditioned stimulus. This is when a formerly neutral stimulus, like the bell in Pavlov's experiment, mimics an unconditioned response, as when the dogs began to associate the bell with food and salivate.
  • Conditioned response. The learned behavior, such as relating the bell to food, is called a conditioned response. 

Classical conditioning theory says that behaviors are learned by connecting a neutral stimulus with a positive one, such as when Pavlov's dogs heard a bell (neutral) and expected food (positive).  

There are essentially three stages in classical conditioning:.

Before conditioning. Something in the environment triggers a natural response in the subject. During this stage, no new behavior has been learned yet. This stage also includes a neutral stimulus, which doesn't affect the subject. To create a response to a neutral stimulus, it must be linked to an unconditioned stimulus -- like the bell to food. 

During conditioning. This is the stage in which the subject starts to associate the neutral stimulus with the positive stimulus that caused the response during the first stage. In Pavlov's experiment, this stage involved ringing a bell when the dogs were fed. Over time, the dogs began to associate the bell with food.

For this to work, the neutral stimulus should come before the positive (unconditioned) stimulus. It creates a cue for what comes next. Doing this over and over makes the conditioning stick. But sometimes it only takes one time to make an association, such as a hangover after too much drinking. 

After conditioning. During the final stage of conditioning, the subject firmly associates the neutral stimulus with the unconditioned response. This creates a new behavior, or what's known as the conditioned response. If the link between the two weakens or breaks, this leads to what's called extinction. When Pavlov's dogs no longer got food after hearing the bell, they eventually stopped associating the bell with food.

Considered one of the "most ethically dubious experiments ever conducted," the Little Albert experiment was developed by psychologists John B. Watson and Rosalie Rayner, who first applied Pavlov's classical conditioning principles to human behavior.

In 1920, Watson and Rayner began their behavioral learning experiment with a 9-month-old boy named Albert. They tested his reactions to various things in his environment, including a white rat, burning newspapers, and a hammer striking a 4-foot steel bar just behind Albert's head. Because the sound of the hammer frightened Albert, it became the unconditioned stimulus, and fear became the unconditioned response.

When Albert was 11 months old, he was presented with the white rat. When he tried to pet it, the pipe was struck with the hammer, causing him to feel fear. The researchers did this over the next few weeks and eventually Albert saw the rat and showed a fearful response. 

They reproduced these results with a rabbit, a dog, and several other stimuli that were previously neutral. At the end of the experiment, Albert showed a fear response for all of them.

Classical conditioning relies on associating one stimulus with another, such as the sound of a bell with food. Learning through operant conditioning relies on what comes after behaviors. These are the consequences that reinforce or punish behaviors.

In operant conditioning, either positive or negative reinforcement is used to affect whether a behavior is likely to happen again.  

When you give your dog a treat after they follow a command, that's positive reinforcement. It encourages them to repeat the behavior. When you yell (punishment) after your dog grabs food off the counter, that's punishment or negative reinforcement. Like classical conditioning, operant conditioning requires repetition for learning to take place. 

Classical conditioning includes several steps:

Acquisition. The point at which the neutral stimulus and unconditioned stimulus become linked. In other words, the dog learns to relate the sound of the bell with food.  

Extinction. Extinction breaks the conditioned bonds between the stimuli. If the dog no longer sees food after hearing the bell, it will gradually stop associating the bell with food.

Spontaneous recovery. If, after extinction, the conditioned stimulus and neutral stimulus again appear in relationship to one another, the conditioned response will return. After the extinction of the conditioned response in his dogs, Pavlov rang the bell before producing the food a few days later. His dogs began to salivate at the sound of the bell again.

Generalization. A conditioned response may be produced with stimuli that are similar but not the same. For example, if Pavlov's dogs heard a bell that rang at a lower pitch and still salivated, that's generalization.

Discrimination. Discrimination is the ability to understand that two or more stimuli are different from one another. In Pavlov's experiment, he later introduced the dogs to two bell sounds. Food appeared only after one. The dogs soon learned the difference. 

Classical conditioning isn't just related to food or fear. You see examples of this type of conditioning every day, though you may not know it or consciously think about it. Here are some examples of classical conditioning in daily life.

  • Every time you put on your shoes, your dog gets excited and runs to the front door. Your dog associates you putting on shoes with a walk, or maybe going for a car ride.
  • You always buy the same type of crackers for your baby's morning snack. When you pull the box of crackers out of the cupboard, your baby gets excited and reaches toward the box because they associate that box with snack time.
  • A certain perfume reminds you of your late grandmother. After her passing, smelling that perfume or similar scents make you sad because of its association with your grandmother.
  • Your demanding boss occasionally berates underperforming employees in his office. You feel nervous or agitated whenever your boss asks one of your co-workers into his office and closes the door because that's what he does whenever someone's in trouble.
  • You listen to your favorite music when you exercise. You don't generally enjoy working out, but eventually, you begin to relate the positive feelings you get from your playlist to working out.
  • Advertising. You see an ad showing a cold, wet can of soda while pumping your gas. You start feeling thirsty and think about running inside and buying this soft drink. 

Psychologists consider classical conditioning a key type of learning. It can create changes in mental and physical health, emotions, and drive. Its uses include: 

  • Phobias. Repeated exposure to the object of a phobia, such as frequently flying when you're afraid of planes, can reduce fears.
  • Drug use. Counselors often urge former addicts to stay away from people and places associated with their drug use.
  • Classroom learning. Teachers might use classical conditioning to associate learning with positive emotions rather than negative ones like fear or shame.
  • Pet training. Classical conditioning taught Pavlov's dogs what to expect after they heard the bell: food. Your dog also learns to positively associate actions like picking up a leash with going for a walk or going out to pee.
  • Food aversions. We're born favoring certain tastes more than others (like sweet vs. bitter). If you eat something and become sick, you might learn to avoid the food and even feel sick at the sight of it. 
  • PTSD  For people with posttraumatic stress disorder (PTSD), classical conditioning may not cure their condition but contribute to it. PTSD is a type of anxiety that comes from associating certain triggers with fearful experiences. For example, loud noises may remind a veteran of the sounds of war. 

Classical conditioning stresses outward learning over traits we're born with. Some criticisms of classical conditioning include:

  • It fails to consider complex human actions like thinking, reason, and memory that produce learning, too. 
  • It takes a long time to make the associations that create learning.
  • It assumes a lack of free will -- that people have no control over their reactions to stimuli.

Classical conditioning is a type of learning by association. It takes several steps to associate a neutral stimulus with a positive outcome. Classical conditioning is used to treat psychological problems such as drug addiction and phobias. But it's also the basis for posttraumatic stress disorder (PTSD). Classical conditioning appears in everyday life in advertising and in our sensory associations with good and bad events. 

  • What is the simple definition of classical conditioning?
    Classical conditioning is learning through association.
  • What is an example of classical conditioning?
    Listening to your favorite music during workouts is an example of associating exercise with a positive neutral stimulus.
  • What are the five elements of classical conditioning? 
    Elements of classical conditioning include acquisition, extinction, spontaneous recovery, generalization, and discrimination.