Conditioned Stimulus in Classical Conditioning

In classical conditioning, the conditioned stimulus is a previously neutral stimulus that, after becoming associated with the unconditioned stimulus, eventually comes to trigger a conditioned response.

How Does Conditioned Stimulus Work?

Ivan Pavlov first discovered the process of classical conditioning in his experiments on the digestive response of dogs. He noticed that the dogs naturally salivated in response to food, but that the animals also began to drool whenever they saw the white coat of the lab assistant who delivered the food.

The previously neutral stimulus (the lab assistant) had become associated with an unconditioned stimulus (the food) that naturally and automatically triggered a response (salivating). After the neutral stimulus had become associated with the unconditioned stimulus, it became a conditioned stimulus capable of triggering the conditioned response all on its own.

Examples of a Conditioned Response

Suppose that the smell of food is an unconditioned stimulus and a feeling of hunger is the unconditioned response. Now, imagine that when you smelled your favorite food, you also heard the sound of a whistle.

While the whistle is unrelated to the smell of the food, if the sound of the whistle was paired multiple times with the smell, the sound alone would eventually trigger the conditioned response. In this case, the sound of the whistle is the conditioned stimulus.

The example above is very similar to the original experiment Pavlov performed. The dogs in his experiment would salivate in response to food, but after repeatedly pairing the presentation of food with the sound of a bell, the dogs would begin to salivate to the sound alone. In this example, the sound of the bell was the conditioned stimulus.

There are plenty of examples of how neutral stimuli can become a conditioned stimulus through association with an unconditioned stimulus. Let's explore a few more examples.

• Bad burrito: You eat a burrito for lunch but become ill shortly after. While the food you ate was previously a neutral stimulus, it becomes a conditioned stimulus through its association with the unconditioned stimulus (illness). As a result, you may develop a taste aversion in which just the idea of eating that same food again causes you to feel ill.
• Dog attack: You are out riding your bike one day and are attacked by a dog. Now, the place where you were attacked has become a conditioned stimulus and you experience fear every time you pass that spot.
• Hotel bell: A hotel concierge begins to respond every time he hears the ringing of a bell. Because the bell has become associated with the sight of customers needing assistance, the bell has become a conditioned stimulus.
• Lunch bell: Students hear the sound of a bell right before they are released for lunch. Eventually, just the sound of the bell alone causes the students to become hungry.