Table of ContentsView AllTable of ContentsExamples of Unconditioned StimuliThe Neutral StimulusUnconditioned vs. Conditioned StimuliTiming of Learned BehaviorTypes of Classical Conditioning

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Table of Contents

Examples of Unconditioned Stimuli

The Neutral Stimulus

Unconditioned vs. Conditioned Stimuli

Timing of Learned Behavior

Types of Classical Conditioning

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In the learning process known asclassical conditioning, the unconditioned stimulus (UCS) is one that unconditionally, naturally, and automatically triggers aresponse. In other words, the response takes place without any prior learning.

Contrast this with the conditioned stimulus, which only prompts a response after a person or animal has learned to associate the stimulus with a certain response.

Unconditioned stimuli are all around us. Think about:

In each of these examples, the unconditioned stimulus naturally triggers an unconditioned response or reflex. You don’t have to learn to respond to the unconditioned stimulus; it occurs automatically.

The Unconditioned Stimulus in Pavlov’s Experiment

InIvan Pavlov’s classic experimentwith dogs, Pavlov and his assistants showed the dogs edible and non-edible items and measured saliva production with each. Salivation occurred automatically and without the dogs' conscious effort when they smelled the food.

This response required no learning. The food was an unconditioned stimulus because it prompted a reflexive response.

The Little Albert Experiment

Building on Pavlov’s work, behavioristJohn B. Watsonand graduate student Rosalie Rayner conducted what came to be known as “the Little Albert experiment.” The research showed that emotional reactions could be classically conditioned in people.

Watson and Rayner exposed a 9-month-old child, Albert, to a white rat, a rabbit, a monkey, masks, and burning newspapers and observed the boy’s reactions. He showed no fear of them at first.

But after Watson began making a loud noise—an unconditioned stimulus that provoked Albert’s crying—whenever he showed Albert the white rat, Albert became frightened whenever he saw the white rat. Because he’d learned to associate the white rat with a noise he feared, he ultimately reacted with fear to the rat as well. The rat, once a neutral stimulus, had become a conditioned stimulus.

A neutral stimulus doesn’t trigger any particular response at first, but when used together with an unconditioned stimulus, it can effectively stimulate learning, eventually becoming a conditioned stimulus. A good example of a neutral stimulus is a sound or a song.

When it is initially presented, the neutral stimulus has no effect on behavior. As it is repeatedly paired with an unconditioned stimulus, it will begin to cause the same response as the UCS.

For example, the assistants in Pavlov’s experiment initially elicited no salivation and therefore were neutral stimuli. Likewise, the sound of a squeaky door opening is initially a neutral stimulus. If that sound is repeatedly paired with an unconditioned stimulus, such as feeding your cat, that sound will eventually come to trigger a change in your cat’s behavior. Once an association has been formed, your cat may react as if it is being fed every time it hears the squeaky door open.

Unconditioned Stimulus vs. Conditioned Stimulus

An unconditioned stimulus causes a response without any prior learning on the part of the subject. The response is automatic and occurs without thought. In contrast, a conditioned stimulus produces a reaction only after the subject has learned to associate it with a given outcome.

In Pavlov’s experiments, the dogs learned to salivate when they saw the assistants' white lab coats because they’d formed an association between the assistants and the food they presented, The salivary response to the assistants was not an automatic, physiological process, but a learned one. The presence of the assistants, initially a neutral stimulus, became a conditioned stimulus.

Throughout the classical conditioning process, a number of factors can influence how quickly associations are learned. The length of time that passes between presenting the initially neutral stimulus and the unconditioned stimulus is one of the most important factors in whether learning occurs.

The timing of how the neutral stimulus and the unconditioned stimulus are presented is what influences whether or not an association will be formed, a principle that is known as the theory of contiguity.

In Pavlov’s experiment, the sound of a buzzer was initially a neutral stimulus, while the smell of food was an unconditioned stimulus. Presenting the tone close to presenting the smell of food resulted in a stronger association. Ringing the buzzer, the neutral stimulus, long before the unconditioned stimulus led to a much weaker or even nonexistent association.

Different types of conditioning may use different timing or order between the neutral stimulus and the UCS.

Insimultaneous conditioning, the neutral stimulus is presented at the exact time as the unconditioned stimulus. This type of conditioning leads to weak learning.Inbackward conditioning, the unconditioned stimulus is given first, and the neutral stimulus is presented afterward. This type of conditioning also tends to result in weak learning.Intrace conditioning, the neutral stimulus is presented briefly and then stopped, then the unconditioned stimulus is presented. This type of conditioning produces good results.Indelayed conditioning, the neutral stimulus is presented and continues while the unconditioned stimulus is offered. This type of conditioning produces the best results.

What Is Acquisition?

3 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Beck HP, Levinson S, Irons G.Finding Little Albert: A journey to John B. Watson’s infant laboratory.Am Psychol.2009;64(7):605-14. doi:10.1037/a0017234Boakes RA, Costa DSJ.Temporal contiguity in associative learning: Interference and decay from an historical perspective.J Exp Psychol Anim Learn Cogn.2014;40(4):381-400. doi:10.1037/xan0000040Prével A, Rivière V, Darcheville J, Urcelay GP.Conditioned reinforcement and backward association.Learn Motivat.2016;56:38-47. doi:10.1016/j.lmot.2016.09.004Additional ReadingPavlov I.Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex. Oxford University Press.

3 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Beck HP, Levinson S, Irons G.Finding Little Albert: A journey to John B. Watson’s infant laboratory.Am Psychol.2009;64(7):605-14. doi:10.1037/a0017234Boakes RA, Costa DSJ.Temporal contiguity in associative learning: Interference and decay from an historical perspective.J Exp Psychol Anim Learn Cogn.2014;40(4):381-400. doi:10.1037/xan0000040Prével A, Rivière V, Darcheville J, Urcelay GP.Conditioned reinforcement and backward association.Learn Motivat.2016;56:38-47. doi:10.1016/j.lmot.2016.09.004Additional ReadingPavlov I.Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex. Oxford University Press.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Beck HP, Levinson S, Irons G.Finding Little Albert: A journey to John B. Watson’s infant laboratory.Am Psychol.2009;64(7):605-14. doi:10.1037/a0017234Boakes RA, Costa DSJ.Temporal contiguity in associative learning: Interference and decay from an historical perspective.J Exp Psychol Anim Learn Cogn.2014;40(4):381-400. doi:10.1037/xan0000040Prével A, Rivière V, Darcheville J, Urcelay GP.Conditioned reinforcement and backward association.Learn Motivat.2016;56:38-47. doi:10.1016/j.lmot.2016.09.004

Beck HP, Levinson S, Irons G.Finding Little Albert: A journey to John B. Watson’s infant laboratory.Am Psychol.2009;64(7):605-14. doi:10.1037/a0017234

Boakes RA, Costa DSJ.Temporal contiguity in associative learning: Interference and decay from an historical perspective.J Exp Psychol Anim Learn Cogn.2014;40(4):381-400. doi:10.1037/xan0000040

Prével A, Rivière V, Darcheville J, Urcelay GP.Conditioned reinforcement and backward association.Learn Motivat.2016;56:38-47. doi:10.1016/j.lmot.2016.09.004

Pavlov I.Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex. Oxford University Press.

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